TUNGSTEN

Tungsten is one of the few pure metals which may be used as a plasma facing material. Tungsten has very low sputtering rate, high melting temperatures, good thermal conductivity, low expansion coefficient and low tritium solubility.

Although tungsten has useful properties for a plasma facing material its disadvantages are its high-Z, low ductility, high activation, afterheat and chemical reactivity with air at high temperatures.

GENERAL PROPERTIES - TUNGSTEN [1]

Physical properties

Boiling Point : 5660 C
Density @ 20 C : 19.3 g/cm3
Melting Point : 3410 C

Electrical properties

Electrical Resistivity @ 20 C : 5.4 u [[Omega]] cm
Cold junction @0 C,
Hot junction @ 100 C : +1.12 mV
Temperature Coefficient @0 - 100 C : 0.0048 K-1
Superconductivity Critical Temperature : 0.0154 K

Thermal properties

Latent Heat of Evaporation : 4009 J/g
Latent Heat of Fusion : 192 J/g
Linear Expansion Coefficient
@ 0 - 100 C : 4.5x10-6 m/m-K
Specific Heat @ 25 C : 133 J/kg-K
Thermal Conductivity, @ 0 - 100 C : 173 W/m-K

Mechanical properties

  Material Condition    Soft              Hard              Polycrystaline     
  Bulk Modulus (GPa)                                        311                
   Hardness-Vickers     360               500                                  
   Poisson's Ratio                                          0.28               
Tensile Strength (MPa)  550-620           1920                                 
  [[sigma]]y  (MPa)     550                                                    
       E (GPa)                                              411

DATA AND CORRELATIONS

The data for the thermal and structural properties of tungsten are presented in Table 1 and are taken from refs [2, 3, 4]. Polynomial correlations of the thermal and structural properties as functions of temperature in degrees K, using the data of Table 1, are as follows:

(1)

(2)

(3)

(4)

Equations (1) to (4) are valid in the temperature range of 293-2500 K.

              Table 1 Thermal and structural properties of TUNGSTEN                                     
   T K     [[rho]]    E GPa      [[nu]]     k W/m-K    C J/kg-K   [[sigma]]  [[alpha]]  
           kg/m3                 ---                              y MPa      (10-6)     
                                                                             m/m-K      
   293     19300.0    408.00     0.280      174.91     132.33                5.250      
   300                407.80     0.280      174.00     132.00                5.248      
   400                404.66     0.280      159.00     137.00                5.305      
   473                402.00     0.280      150.12     138.44                5.350      
   600                396.61     0.280      137.00     142.00                5.419      
   800                386.42     0.280      125.00     145.00                5.533      
   873                382.00     0.290      121.60     146.67                5.550      
  1000                374.36     0.290      118.00     148.00                5.646      
  1073                370.00     0.290      115.33     149.68                5.760      
  1200                360.69     0.290      113.00     152.00                5.700      
  1273                355.00     0.290      111.43     152.74                5.800      
  1473                340.00     0.290      108.39     156.17                5.920      
  1500                337.74     0.290      107.00     157.00                5.931      
  2000                295.17     0.230      100.00     167.00                6.215      
  2500                250.77     0.290      95.00      176.00                6.500      


      k (W/m-K)      c (J/kg-K)

Temperature (K)

Figure 1 : Thermal conductivity and specific heat of tungsten.



      E (GPa)      [[alpha]] (10-6 m/m-K)

Temperature (K)

Figure 2 : The elastic modulus and thermal expansion coefficient of tungsten.



References

  1. Goodfellow. Metals, Alloys, Compounds, Ceramics, Polymers, Composites. Catalogue 1993/94.]

  2. Frank P. Incropera, David P. Dewitt. Fundamentals of Heat and Mass Transfer, Second Edition,1985.

  3. Ivica Smid, Masato Akiba, Masanori Araki, Satoshi Suzuki and Kazuyoshi Satoh. Material and Design considerations for the Carbon Armored ITER Divertor. July 1993.

  4. ITER Documentation Series No 29, IAEA, Vienna 1991. "Blanket, Shield Design and Material Data Base".