| Sinter products can be produced in many different ways. One of the most common methods is mixing a fine powder with an organic binder. From this mixture, a so-called green body with a specific geometry can be shaped, for example, by means of cold-isostatic pressing. |
| The first step of subsequent production process is the burnout of polymeric binder by thermal treatment. |
| The speed of this process must be controlled very well. If the speed is too high, then micro-cracks are produced in the green body, because the created gases do not have enough time to diffuse out from the inside. Otherwise, if the speed is too slow, then much time is consumed, leading to an increase in production effort. |
| The experience clearly demonstrates that the best temperature profile for the burnout of the binder shows a constant mass loss rate. Therefore, the aim of investigation of this process is the determination of a set of temperature profiles for various levels of constant mass loss rate. |
| This problem can be solved experimentally by various measurements, executed under the condition of a constant mass loss rate. Much more universally and also much cheaper is the combination of a series of measurements, executed with constant but different heating rates, with the kinetic analysis. This way will be demonstrated in the following: |
| Measurement |
| Instrument: |
NETZSCH TG 209 C Iris® |
| Temperature range/°C: |
RT ... 800 |
| Heating rates/(K/min): |
0.01 .. 10 |
| Atmosphere/(ml/min): |
N2; 20 |
| Sample mass/mg: |
40 .. 50 |
|
| |
 |
| TGA measurements of their fit by a multiple step reaction |
| Using the presented model it is possible to approximate all measurements with a high quality. The higher the fit quality, the more confident the predictions are. |
| |
 |
| Temperature profile for a mass loss rate of 0.5%/min, estimated on the basis of TGA measurements. |
| It is very easy and fast to determine the temperature profile for another value of mass loss rate. |
| |
| Temperature Program for a Mass Loss Rate of 0.5%/min |
| # |
Temperature/°C |
Scan rate/(K/min) |
Total time/min |
| 0 |
50.0 |
|
0.00 |
| 1 |
142.7 |
10.00 |
9.26 |
| 2 |
152.5 |
9.73 |
10.27 |
| 3 |
156.2 |
2.04 |
12.09 |
| 4 |
160.1 |
2.09 |
13.95 |
| 5 |
165.8 |
3.03 |
15.84 |
| 6 |
172.7 |
3.65 |
17.73 |
| 7 |
179.7 |
3.65 |
19.62 |
| 8 |
186.1 |
1.84 |
23.20 |
| 9 |
187.2 |
0.30 |
26.84 |
| 10 |
188.8 |
0.32 |
31.60 |
| 11 |
204.9 |
0.50 |
64.22 |
| 12 |
211.1 |
0.64 |
73.85 |
| 13 |
218.6 |
0.79 |
83.39 |
| 14 |
226.7 |
0.87 |
92.70 |
| 15 |
237.4 |
1.13 |
102.19 |
| 16 |
249.9 |
1.39 |
111.23 |
| 17 |
265.5 |
1.62 |
120.85 |
| 18 |
289.7 |
2.48 |
130.61 |
| 19 |
329.4 |
4.08 |
140.36 |
| 20 |
369.6 |
4.28 |
149.74 |
| 21 |
381.9 |
1.40 |
158.55 |
| 22 |
389.2 |
0.77 |
168.04 |
| 23 |
402.3 |
1.35 |
177.72 |
| 24 |
426.2 |
2.37 |
187.82 |
| 25 |
454.9 |
5.63 |
192.91 |
| 26 |
490.6 |
9.89 |
196.53 |
| 27 |
600.3 |
10.00 |
207.49 |
|
| This temperature program can be exported as an ASCII file and transferred in any program. |
Thermokinetics
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