كربيد الزركونيوم

(تم التحويل من Zirconium carbide)
Zirconium carbide
Zirconium carbide in the unit cell
Powder of zirconium carbide
الأسماء
أسماء أخرى
Zirconium(IV) carbide
المُعرِّفات
رقم CAS
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.031.920 Edit this at Wikidata
رقم EC
  • 235-125-1
رقم RTECS
  • ZH7155000
UN number 3178
الخصائص
الصيغة الجزيئية CZr
كتلة مولية 103.23 g mol-1
المظهر Gray refractory solid
الرائحة Odorless
الكثافة 6.73 g/cm3 (24 °C)[1]
نقطة الانصهار
نقطة الغليان
قابلية الذوبان في الماء Insoluble
قابلية الذوبان Soluble in concentrated H2SO4, HF(aq),[1] HNO3
البنية
البنية البلورية Cubic, cF8[2]
الزمرة الفراغية Fm3m, No. 225[2]
ثابت العقد a = 4.6976(4) Å[2]
ثابت العقد α = 90°, β = 90°, γ = 90°
Octahedral[2]
الكيمياء الحرارية
الإنتالپية المعيارية
للتشكل ΔfHo298 		−207 kJ/mol (extrapolated to stoichiometric composition)[3]
−196.65 kJ/mol[4]
Standard molar
entropy So298 		33.14 J/(mol·K)[4]
سعة الحرارة النوعية، C 37.442 J/(mol·K)[4]
المخاطر
خطر رئيسي Pyrophoric
ن.م.ع. مخطط تصويري الرمز التصويري للهب في النظام المنسق عالمياً لتصنيف وعنونة الكيماويات (GHS)The exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)[5]
ن.م.ع. كلمة الاشارة Danger
H228, H302, H312, H332[5]
P210, P280[5]
NFPA 704 (معيـَّن النار)
Flammability code 0: لن يشتعل. مثل الماءHealth code 0: التعرض تحت ظروف النار لن يشكل خطراً أكثر من مادة عادية قابلة للاشتعال. مثل كلوريد الصوديومReactivity code 0: مستقر في العادة، حتى تحت ظروف التعرض للنار، ولا يتفاعل مع الماء. مثل النيتروجين السائلSpecial hazards (white): no codeNFPA 704 four-colored diamond
0
0
0
مركبات ذا علاقة
Zirconium nitride
Zirconium oxide
Titanium carbide
Hafnium carbide
Vanadium carbide
Niobium carbide
Tantalum carbide
Chromium carbide
Molybdenum carbide
Tungsten carbide
Silicon carbide
ما لم يُذكر غير ذلك، البيانات المعطاة للمواد في حالاتهم العيارية (عند 25 °س [77 °ف]، 100 kPa).
YesY verify (what is YesYX mark.svgN ?)
مراجع الجدول

Zirconium carbide (ZrC) is an extremely hard refractory ceramic material,[6] commercially used in tool bits for cutting tools. It is usually processed by sintering.

Properties

Thermal expansion coefficients of ZrC[7]
T αV
[units?]
100 °C 0.141
200 °C 0.326
400 °C 0.711
800 °C 1.509
1200 °C 2.344

It appears as a gray metallic powder with cubic crystal structure. It is highly corrosion resistant. This group IV interstitial transition-metal carbide is also an example of ultra high temperature ceramics (UHTC). Due to the presence of metallic bonding, ZrC has a thermal conductivity of 20.5 W/(m·K) and an electrical conductivity of around 2.3 megasiemens per metre, both of which are similar to that for zirconium metal. The strong covalent Zr-C bond gives this material a very high melting point (~3530 °C), high elastic modulus (~440 GPa) and hardness (25 GPa). ZrC has a lower density (6.73 g/cm3) compared to other carbides like WC (15.8 g/cm3), TaC (14.5 g/cm3) and HfC (12.67 g/cm3). ZrC seems suitable for use in re-entry vehicles, rocket/scramjet engines or supersonic vehicles in which low densities and high temperature load-bearing capabilities are crucial requirements.[بحاجة لمصدر]

Like most carbides of refractory metals, zirconium carbide is sub-stoichiometric, i.e., it contains carbon vacancies. At carbon contents higher than approximately ZrC
0.98 the material contains free carbon.[3] ZrC is stable for a carbon-to-metal ratio ranging from 0.65 to 0.98.

The group IV and group IVa element carbides, TiC, ZrC, and SiC are practically inert toward attack by strong aqueous acids (e.g. HCl(aq)) and strong aqueous bases (NaOH) even at 100 °C, however, ZrC does react with HF.

The mixture of zirconium carbide and tantalum carbide is an important cermet material.[بحاجة لمصدر]

Uses

Hafnium-free zirconium carbide and niobium carbide can be used as refractory coatings in nuclear reactors. Because of a low neutron absorption cross-section and weak damage sensitivity under irradiation, it finds use as the coating of uranium dioxide and thorium dioxide particles of nuclear fuel. The coating is usually deposited by thermal chemical vapor deposition in a fluidized bed reactor. It also has high emissivity and high current capacity[مطلوب توضيح] at elevated temperatures, rendering it a promising material for use in thermo-photovoltaic radiators and field emitter tips and arrays.[بحاجة لمصدر]

It is also used as an abrasive, in cladding, cermets, incandescent filaments and cutting tools.[بحاجة لمصدر]

Production

Zirconium carbide can be fabricated in several ways. One method is carbothermic reaction of zirconia by graphite. This results in a powder. Densified ZrC can then be made by sintering the powder of ZrC at upwards of 2000 °C. Hot pressing of ZrC can bring down the sintering temperature and consequently helps in producing fine grained fully densified ZrC. Spark plasma sintering also has been used to produce fully densified ZrC.[8]

Zirconium carbide can also be fabricated by solution based processing.[9] This is achieved by refluxing a metal oxide with acetylacetone.

Another method of fabrication is chemical vapour deposition.[10] This is achieved by heating a zirconium sponge and passing halide gas through it.

Poor oxidation resistance over 800 °C limits the applications of ZrC. One way to improve the oxidation resistance of ZrC is to make composites. Important composites proposed are ZrC-ZrB
2 and ZrC-ZrB
2-SiC. These composites can work up to 1800 °C.[بحاجة لمصدر] Another method to improve this is to use another material as a barrier layer, such as in TRISO fuel particles.

References

  1. ^ أ ب خطأ استشهاد: وسم <ref> غير صحيح؛ لا نص تم توفيره للمراجع المسماة crc
  2. ^ أ ب ت ث Kempter, C. P.; Fries, R. J. (1960). "Crystallographic Data. 189. Zirconium Carbide". Analytical Chemistry. 32 (4): 570. doi:10.1021/ac60160a042.
  3. ^ أ ب Baker, F. B.; Storms, E. K.; Holley, C. E. (1969). "Enthalpy of formation of zirconium carbide". Journal of Chemical & Engineering Data. 14 (2): 244. doi:10.1021/je60041a034.
  4. ^ أ ب ت قالب:Nist
  5. ^ أ ب ت Sigma-Aldrich Co., Zirconium(IV) carbide. Retrieved on 2014-06-30.
  6. ^ Measurement and theory of the hardness of transition- metal carbides, especially tantalum carbide. Schwab, G. M.; Krebs, A. Phys.-Chem. Inst., Univ. Muenchen, Munich, Fed. Rep. Ger. Planseeberichte fuer Pulvermetallurgie (1971), 19(2), 91-110
  7. ^ خطأ استشهاد: وسم <ref> غير صحيح؛ لا نص تم توفيره للمراجع المسماة hicse
  8. ^ Wei, Xialu; Back, Christina; Izhvanov, Oleg; Haines, Christopher; Olevsky, Eugene (2016). "Zirconium Carbide Produced by Spark Plasma Sintering and Hot Pressing: Densification Kinetics, Grain Growth, and Thermal Properties". Materials. 9 (7): 577. Bibcode:2016Mate....9..577W. doi:10.3390/ma9070577. PMC 5456903. PMID 28773697.
  9. ^ Sacks, Michael D.; Wang, Chang-An; Yang, Zhaohui; Jain, Anubhav (2004). "Carbothermal reduction synthesis of nanocrystalline zirconium carbide and hafnium carbide powders using solution-derived precursors". Journal of Materials Science. 39 (19): 6057–6066. Bibcode:2004JMatS..39.6057S. doi:10.1023/B:JMSC.0000041702.76858.a7. S2CID 94979802.
  10. ^ Yiguang Wang; Qiaomu Liu; Jinling Liu; Litong Zhang; Laifei Cheng (January 2008). "Deposition Mechanism for Chemical Vapor Deposition of Zirconium Carbide Coatings". Journal of the American Ceramic Society. 91 (4): 1249–1252. doi:10.1111/j.1551-2916.2007.02253.x. Retrieved 2021-12-27.
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