Densification and microstructure changes of micron size nickel powder during direct induction sintering

Abstract

International audienceInduction heating is an attractive technique to sinter metal powders in a short time and with limited energy. A series of direct induction sintering experiments has been performed with a micron size nickel powder in a dedicated set-up with 50 or 150 kHz current frequency and several heating rates, up to 900 degrees C min(-1). With a view to better catching the specific outcome of induction sintering, conventional sintering tests have also been achieved and their results in terms of densification have been depicted by adjusting a Master Sintering Curve model. The main conclusion of this study is that nickel specimens with high density, reasonably low grain size and homogeneous microstructure can be obtained by direct induction sintering with processing times much smaller than typical conventional sintering times. The obtained data also show that powder densification is accelerated during induction sintering, which is supposedly due to the enhancement of diffusion under electric curren

Progress in aluminium and magnesium matrix composites obtained by spark plasma, microwave and induction sintering

“…Induction sintering is based on the use of eddy currents induced in an electrically conductive material [40,41]. The penetration depth of the eddy currents h is determined as…”

“…Induction sintering is based on the use of eddy currents induced in an electrically conductive material [40,41]. The penetration depth of the eddy currents h is determined as where is the frequency, is the material magnetic permeability and is the material electrical conductivity.…”

On the swelling of silver powder during sintering

“…Thus, investigating the influence of heating rate on powder swelling is valuable. For this purpose, direct induction sintering tests have been performed with the set-up developed by Guyon et al 11 The penetration depth of eddy currents has been estimated to be around 500 µm at sintering temperature, i.e. much smaller than the diameter of the specimens.…”

Indirect Induction Sintering of Metal Parts Produced through Material Extrusion Additive Manufacturing

“…The solid-state sintering of powder compacts results from the reduced surface energy of particles in close proximity, whereby mass transport diffusion takes place, with the most common approach performed through solid-state furnace sintering [ 35 ]. Other highly effective routes have been developed more recently, such as microwave sintering [ 36 , 37 ], Spark Plasma Sintering (SPS) or Field-Assisted Sintering (FAST) [ 38 ], or via direct [ 39 , 40 , 41 ] or indirect [ 42 , 43 ] induction. An advantage of microwave, SPS/FAST, and induction sintering, in contrast to conventional sintering, is the capability to sinter in only a few minutes rather than hours or days [ 36 , 38 , 41 ].…”

“…Other highly effective routes have been developed more recently, such as microwave sintering [ 36 , 37 ], Spark Plasma Sintering (SPS) or Field-Assisted Sintering (FAST) [ 38 ], or via direct [ 39 , 40 , 41 ] or indirect [ 42 , 43 ] induction. An advantage of microwave, SPS/FAST, and induction sintering, in contrast to conventional sintering, is the capability to sinter in only a few minutes rather than hours or days [ 36 , 38 , 41 ]. Low sintering times are possible with microwaves, SPS, and induction since high heating rates are attained due to the internal heating of the part as opposed to the external heating of conventional furnace sintering.…”