This paper discusses how the estimation of the temperature field in the powder bed in selective laser sintering is a key issue for understanding sintering/binding mechanisms and for process optimisation. Carried out within a European research project, funded by INTAS (No. 99-1559, 2000-02), a model of independent small thermal contacts to calculate the effective contact conductivity in Ti powder bed was developed. This paper won the Emerald Literati Awards' Outstanding Paper 2004 (http://www.emeraldinsight.com/literaticlub/winners).Coupled metallographic examination and heat transfer numerical simulation are applied to reveal the laser sintering mechanisms of Ti powder of 63-315?µm particle diameter. A Nd:YAG laser beam with a diameter of 2.7-5.3?mm and a power of 10-100?W is focused on a bed of loose Ti powder for 10?s in vacuum. The numerical simulation indicates that a nearly hemispherical temperature front propagates from the laser spot. In the region of a-Ti just behind the front, heat transfer is governed by thermal radiation. The balling effect, formation of melt droplets, is not observed because the temperature increases gradually and the melt appears inside initially sintered powder which resists the surface tension of the melt. (Emerald Publishing Group Limited

We present the results of analysis of the errors introduced by hot-band transitions 11 1 0-01 1 1, 03 1 0-01 1 1, 12 0 0-12 0 1 of the CO 2 molecule and the absorption lines of the H 2 O and NO 2 molecules in determination of the temperature and partial pressure of CO 2 , included in the gas mixture CO 2 :N 2 :H 2 O:NO 2 at atmospheric pressure, by multiple-frequency laser probing using a CO 2 laser tunable over the lines of the 00 0 1-[10 0 0,02 0 0] I,II ground-state laser transitions.

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