Liquid Metal Infiltration processed is used for infiltrating ceramic perform with liquid metal. This is a very important process for technical application and is often for high particle contents.
For the prefrom production preform ceramic particles are mixed with a binder and subsequently cold-isostatic pressed. The resulting, so called, green compact, will now undergo a sintering process at high temperatures. During this process the binder will be out gassed. A three dimensional open porous structure results after sintering. Because it is open porous the metal can flow in. The particles are connected together so the preform has some stability. This eases the handling of these performs. Within some geometrical limitations near-net-shape parts could be made. Minimum particle content is about 30% up to max. 70%. Dependent on the particle system 35-55% is useful for most of the liquid metal infiltrated Composites. Several particle systems could be used for the perform like Al2O3, SiC, AlN, TiC, TiB and others. However the majority of preforms is made with Alumina and Silicon-Carbide particles. Ovens used for sintering the preform are usually very large because they are also used for conventional technical ceramic production. This makes this process very economical. Thousands of performs could be sintered at the same time.
The ceramic perform is heated up to approximately 800°C before the infiltration with the liquid metal to avoid a fast solidification. Infiltration process is Squeeze Casting. This process is very comparable to pressure die casting. Infiltration is done within seconds. The ceramic preform “soaks” the metal.
More Information in the menu item, Aluminum high temperature, DSC-Materials.