Effects of Elemental Additives on Electrical Resistivity of Silicon Carbide Ceramics

Abstract

Effects of various elemental additives on the electrical resistivity of hot‐pressed SiC ceramics were studied. The electrical resistivity at room temperature of dense SiC ceramics varied greatly depending on the additives used. SiC ceramics with added Be had an extremely high electrical resistivity of 3 × 1012°.cm. On the other hand, SiC ceramics with added B and Al had electrical resistivities of 2 × 10 and 0.8 °cm, respectively. The differences in the electrical resistivity of the dense SiC ceramics were considered to be due to different solubilities of the additives in SiC grains. SiC ceramics with added Be had a low level of impurities in the SiC grains as a result of the low solubility of Be in these grains.

Microstructure, Thermal Conductivity, and Electrical Properties of In Situ Pressureless Densified SiC–BN Composites

“…In addition, the annealing posttreatment was beneficial for improving the thermal conductivities of all the samples owing to the effects of grain growth and elimination of crystal defects. The thermal conductivities of these SiC–BN composites were all higher than the 60 W·(m·K) −1 in SiC ceramics doped with 1 wt% Al reported previously …”

“…Unfortunately, polycrystalline SiC is commonly a semiconductor and still has several weaknesses for the above applications, including insufficiently high electrical resistivity, as well as excessive dielectric constant and loss . The highest thermal conductivity of 270 W·(m·K) −1 and high electrical resistivity of 10 13 Ω·cm at room temperature have been reported for SiC ceramics doped with BeO . However, the usage of toxic beryllia cannot meet the demand of environmental protection nowadays.…”

Effects of Y2O3–RE2O3 (RE = Sm, Gd, Lu) Additives on Electrical and Thermal Properties of Silicon Carbide Ceramics

“…The electrical conductivity of polycrystalline SiC ceramics is strongly dependent on additive composition and sintering atmosphere . The electrical conductivities of SiC ceramics sintered in an argon atmosphere are as follows: 5.0 × 10 −3 (Ω·m) −1 for SiC ceramics sintered with 1 wt% B; 2 × 10 −2 –1.3 × 10 2 (Ω·m) −1 for SiC ceramics sintered with 1 wt% Al; 3.3 × 10 −12 (Ω·m) −1 for SiC ceramics sintered with 1 wt% Be; 1.0 × 10 −9 (Ω·m) −1 for SiC ceramics sintered with 10 wt% Al 2 O 3 –Y 2 O 3 ; 1.0 × 10 0 –7.7 × 10 −9 (Ω·m) −1 for SiC ceramics sintered with 3 vol% AlN–Y 3 Al 5 O 12 ; 2.8 × 10 −10 (Ω·m) −1 for SiC ceramics sintered with 7 wt% Al 2 O 3 –Er 2 O 3 ; 5.6 × 10 −7 (Ω·m) −1 for SiC ceramics sintered with 7 wt% Y 2 O 3 –Al 2 O 3 –CaO; 9.1 × 10 −4 (Ω·m) −1 for SiC ceramics sintered with 10 wt% Al 2 O 3 –Y 2 O 3 –AlN …”

Silicon carbide membranes for gas separation applications

“…A promising candidate material for a variety of inorganic membrane applications is SiC due to its many unique properties, such as high thermal conductivity [1], thermal shock resistance [2], biocompatibility [3], resistance in acidic and alkali environments [4], chemical inertness, and high mechanical strength [5,6]. There are relatively few reports discussing the preparation of SiC membranes.…”