Joints matching coefficient

Zhao X, 1997a, Joint surface matching and shear strength. Part A joint matching coefficient(JMC) [J]. Int. J. Rock Mech. Min. Sci Geomech. Abstr., 34(2) 173-178. 

The ceramic membrane typically must also be joined to a metal manifold to collect the product gas. The requirements of ceramic-metal joints are extremely stringent due to the large pressure differential across the membrane. Even very small leaks will create a drop in product purity. The joints are usually at the operating temperature, although cold seals are occasionally considered. The thermal expansion coefficient of the ceramic needs to match that of the metal manifold. 

Lao 75Cao,25) 1.01 Fe03 is formed at the seal. Since the third multicomponent metalUc oxide is identical to the composition of the ceramics to be joined, the thermal expansion coefficient of the joint material closely matches the thermal expansion coefficient of the (Lao.75Cao,25)i,oiFe03 parts that were joined. The joint thus has about the same thermal cycUng stability as the parts themselves. The joint also has the same chemical properties as the membrane material and therefore, the seal will be as resistant to the process atmospheres as the membrane material itself There are also no concerns with reactivity or chemical incompatibility of the seal material and the membrane material since the membrane and the joint material are chemically identical after the joint has been made. The invention of Butt et al. [33, 34] thus produces a ceramic-to-ceramic seal that has the very attractive properties of being expansion matched to the membrane material chemically identical to the membrane material just as chemically compatible with the process gas atmospheres as the membrane material just as thermodynamically... 

Scarf repairs can be modelled to a first approximation as a simple scarf joint. If the patch matches the parent material in stifliiess and expansion coefficient, simple theory... 

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