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微波工程期中報告
論文研討:
 K. Saitou, “Microwave sintering of iron,
cobalt, nickel, copper and stainless steel
powders”,Scripta Materialia 54 (2006) 875–879
報告人:
碩研電子一甲 MA030118
Southern Taiwan University
吳宗勳
Department of Electronic Engineering
Abstract

Metal powder compacts were sintered using single mode microwave
radiation. The results of microwave sintering were compared with those
of conventional sintering.

Microwave sintering promoted greater shrinkage than conventional
sintering.

The sintering behavior of Fe compacts around the A3 transformation
temperature was significantly affected by microwave radiation.
K. Saitou / Microwave sintering of iron, cobalt, nickel, copper and stainless steel powders
Scripta Materialia 54 (2006) 875–879
1
Experimental procedure

Powders were heated in an oven at 150°C in air to eliminate moisture.

The powders were pressed into green compacts with dimensions of 12 mm
diameter and 7.6–10 mm thick.

The green compacts were sintered after the dimensions
and weights were measured. Sintering was performed
using two methods, MW and conventional electric furnace(EF) heating.
K. Saitou / Microwave sintering of iron, cobalt, nickel, copper and stainless steel powders
Scripta Materialia 54 (2006) 875–879
2
Experimental procedure

Fig. 1 shows a schematic of the
applicator. At first,the green compact
was inserted into a boron nitride (BN)
tube

The MW sintering temperature was
controlled manually using the calibrated
pyrometer, and the heating rate was
maintained at a constant 80 K/min
throughout the entireMW sintering
process.
K. Saitou / Microwave sintering of iron, cobalt, nickel, copper and stainless steel powders
Scripta Materialia 54 (2006) 875–879
3
Experimental procedure
Table 1. After sintering, the density of the specimens was calculated by
dimension and weight measurements, or by the Archimedesmethod.
K. Saitou / Microwave sintering of iron, cobalt, nickel, copper and stainless steel powders
Scripta Materialia 54 (2006) 875–879
4
Results and discussion

Fig. 2 shows Arrhenius plots
for the shrinkage parameters
of Co, Ni, SUS 316L and
Cu sintered powders.
K. Saitou / Microwave sintering of iron, cobalt, nickel, copper and stainless steel powders
Scripta Materialia 54 (2006) 875–879
5
Results and discussion

Fig. 3 shows an Arrhenius plot
for the shrinkage of an Fe
powder compact.

It is widely known that Fe
transforms from body-centered
cubic (bcc) to face-centered
cubic (fcc) at 910 °C (A3), and
from fcc to bcc at 1390 °C (A4),
and these temperatures are
indicated in Fig. 3.
K. Saitou / Microwave sintering of iron, cobalt, nickel, copper and stainless steel powders
Scripta Materialia 54 (2006) 875–879
6
Results and discussion
Table. 2. shows the activation energy, Qa, calculated from Figs. 2 and 3.
Activation energies for Fe are in the fccregion. Using Eq.
K. Saitou / Microwave sintering of iron, cobalt, nickel, copper and stainless steel powders
Scripta Materialia 54 (2006) 875–879
7
Conclusion

Except for Fe in the fcc region, MW radiation promoted the sintering of metal
powders, but it did not affect the activation energy for sintering.

MW radiation affected the sintering behavior of Fe around the A3 temperature.
Below this temperature, MW radiation promoted sintering, but retarded sintering
above this temperature.
K. Saitou / Microwave sintering of iron, cobalt, nickel, copper and stainless steel powders
Scripta Materialia 54 (2006) 875–879
8