Thermal expansion matching

Euture appHcations may involve use of SiC as substrates for siHcon chips, making use of the high thermal conductivity of SiC and its close thermal expansion match to siHcon. The low density and high stiffness of siHcon carbides may also result in appHcations in space. One such appHcation is for space-based mirrors, making use of the high degree of surface poHsh possible on dense SiC. 

To reduce the formation of carbon deposited on the anode side [2], MgO and Ce02 were selected as a modification agent of Ni-YSZ anodic catalyst for the co-generation of syngas and electricity in the SOFC system. It was considered that Ni provides the catalytic activity for the catalytic reforming and electronic conductivity for electrode, and YSZ provides ionic conductivity and a thermal expansion matched with the YSZ electrolyte. 

Compared to glass, glass-ceramics are mechanically stronger, more resistant to chemical attack and have a wider range of thermal expansion coefficients. Complex non-linear thermal expansion characteristics can be achieved, resulting in very close thermal expansion matching to a variety of metals and alloys, including those with non-linear behaviour [24],... 

Preferred mixed conducting oxides for ITM oxygen compositions are generically represented by the formula LaxA COyFey-Cuy /Os-z where A is selected from Sr, Ba, Ca, or Mg, and z is a number that makes the composition charge neutral. Selection of A is based on achieving low expansion of the dense phase with temperature. Copper provides improved control over dimensional changes when used in the mix with cobalt and iron, and a coefficient of thermal expansion matches with the substrate. This composition also provides superior resistance when used in the presence... 

For multilayer applications the functional material is commonly a glass or a glass-ceramic. It must have a low dielectric constant and be thermal expansion matched to the substrate to prevent stresses that can cause the substrate to bow. The film must also be stable as it may be subjected to many firing cycles in the fabrication of a multilayer structure. 

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