Comparison between Microwave and Microwave Plasma Sintering of Nickel Powders
The objective of this study is to investigate the use of microwave plasma treatments as a processing technology for the sintering of metal powders. The volumetric heating process achieved with microwaves is considerably more efficient compared with resistance heating. The sintering study was carried out on 20 mm diameter by 2 mm thick compacted discs of nickel powder, with mean particle size of 1 µm. The discs were fired in a 5 cm diameter microwave plasma ball, under a hydrogen atmosphere at a pressure of 2 kPa. There was an increase in fired pellet transverse rupture strength (TRS) with plasma treatment duration. The mechanical properties of the sintered nickel discs were compared based on TRS, Rockwell hardness tests and density measurements. The morphology of the sintered discs was compared using microscopy and SEM. Comparison disc sintering studies were carried out using both a non plasma microwave and tube furnace firing. Using the microwave plasma sintering process full sintered disc strength of ≈1000 N (based on 3-point bend tests) was achieved after a 10 minute treatment time. In contrast the sintering time in the tube furnace treatment involved total processing time of up to 6 hours. The non plasma microwave system involved intermediate treatment periods of 2 hours. The degree of sintering between the individual nickel powder particles can be precisely controlled by the duration of the treatment time in the plasma.
Ionel Chicinaş and Liviu Brânduşan
A. P. Breen et al., "Comparison between Microwave and Microwave Plasma Sintering of Nickel Powders", Materials Science Forum, Vol. 672, pp. 289-292, 2011