Ceramic powder processing machining

Sintering machines, 26 565 molybdenum, 17 9-10 of polytetrafluoroethylene, 18 300-301 phosphate ore, 19 7 Sintering process, 10 41, 94, 95 for ceramic membranes, 15 814, 815 sulfur recovery from, 23 772 with tin powder, 24 798-799 Sinter processes... 

The compression of a powder is a complex process that is usually affected by different kinds of problems. These problems have been widely investigated and mainly concern the volume reduction and the development of a strength between the particles of the powder sufficient to ensure tablet integrity [82], The application of ultrasonic energy shows a great ability to reduce and even avoid these problems [83], Ultrasound refers to mechanical waves with a frequency above 18 kHz (the approximate limit of the human ear). In an ultrasound compression machine, this vibration is obtained by means of a piezoelectric material (typically ceramics) that acts as a transducer of alternate electric energy of different frequencies in mechanical energy. An acoustic coupler, or booster, in contact with the transducer increases the amplitude of the vibration before it is transmitted (usually in combination with mechanical pressure) to the material to be compressed. 

Particularly ceramic and metal powders are formed and densified by pressure agglomeration techniques to yield intermediate products which are heat treated (sintered) to reach final shape, density, and strength. Since many of these materials can not be easily machined after sintering due to their abrasiveness and/or hardness, "near net shape articles are often desired. This means, that, after taking into consideration the dimensional changes caused by, during, and after the sintering process, the part should posses dimensions which need no or minimal adjustment for its intended use. 

---