Industrial Applications

Filters
Some obvious examples of parts that need to be porous are filters for gases and liquids. MIT's three dimensional printing process has been used in the past to fabricate large, efficient ceramic filters for coal-fired power stations, diesel engines and food manufacturing applications. Recently Entegris Corp. has received patents on complex filters made in a similar way to remove bases such as ammonia, amines and imides from a semiconductor manufacturing atmosphere. Filters made by rapid manufacturing are generally geometrically complex and offer improved characteristics such as low back-pressure. Additional work is going in filter fabrication for biomedical and life science applications especially using SLS technology.

Gas Storage Cells
Compressed gas storage cells are also components that are porous and have much in common structurally with filters. Applications such as the storage of fuel for hydrogen-powered vehicles are under investigation. Storage cells may be fabricated using selective laser sintering, and one advantage cited is that they can be designed to prevent catastrophic failure in the event a portion of the storage volume is ruptured. Materials and Electrochemical Research Corp. has received a patent for a cell that is self-sealing in the event of a leak or rupture. Similar microporous parts can also be used as energy absorbers for crash protection and as heat exchangers.

    

Batteries
Batteries are doubly interesting for fabrication by RM because they're generally layered structures to begin with, and controlled porosity can provide increased power density and/or efficiency. As one example, three dimensional printing and self-organizing assembly techniques are being investigated to fabricate electrodes and battery structures with very high power density for vehicle applications by A123Systems, Inc.

Small batteries are also being investigated and much of the work is being done using direct-write technologies. Alkaline and other types of microbatteries have been fabricated, as well as integrated assemblies of zinc-air batteries and electromechanical devices. Most of this work is being conducted at the university level at present. It can be expected to move ahead commercially in lock-step with MEMS and nano-device applications that will require appropriately-scaled power sources.

Porous Machine Parts
Mold-Masters Ltd. (Canada) has received several patents for the fabrication of heated manifolds, nozzles and similar components used in injection molding. The devices are made from powdered metals or other materials and infiltrated with thermally conductive materials. Here again, additive fabrication provides greater functionality than can be obtained with standard techniques.