Full Densification of Molybdenum Powders Using Spark Plasma Sintering

Abstract

Pure molybdenum powder was sintered using Spark Plasma Sintering under various temperatures, and holding times, under a pressure of 77 MPa and a heating rate at 700°C/min. After sintering, a carbide layer was observed at the surface. The carbide layer thickness, the relative density of the sample as well as the microhardness and the grain size of Mo were measured. The carbide thickness depends on time and temperature and it was found that the carbide layer grows in a parabolic manner, with the activation energy of carbon diffusion in Mo being equal to 34 Kcal/mol. The densification of Mo is controlled mainly by the sintering temperature and the holding time. The molybdenum powder was successfully consolidated by SPS in short times. A relative density of 100% is achieved at a sintering temperature of 1850°C and a holding time of 30 minutes. It was shown that the hardness decreases slightly with temperature and time. It should be related to the increase in grain size with the sintering temperature and time.

Prologue: The New Era of Sintering

“…The advantage of HIP is the reduction of production times and the variation of properties in the solid, obtaining almost finished parts and parts with complex shapes or small sizes due to its isostatic processing. It is noteworthy in this instance that the model used will be validated over similar powder forming processes where the application of temperature and pressure is performed simultaneously [26][27][28].…”

Sintered molybdenum for a metallized ceramic substrate packaging for the wide-bandgap devices and high temperature applications

“…The disadvantages are: (i) it is very difficult in achieving full densification and (ii) very difficult to assembly with AlN without any additives using standard solution [9]. Preliminary results in the densification of pure Molybdenum shows that a full densification can be obtained using a new sintering technique such as Spark Plasma Sintering [10]. We suggest to use the same sintering technique to realize both molybdenum powder sintering, and Mo / AlN layers bonding simultaneously.…”

“…At the end of each experiment, the samples were crosssectioned, mounted in a hot mounting resin (Presi Phenolic resin) and then prepared metallographically (mechanical a. Molybdenum sintering parameters reported in [10] grinding and polishing down to 0,05 µm silica slurry). The samples were examined using optical and scanning electron microscopy (SEM).…”

“…The sintering of the molybdenum powder using a SPS is presented in details in [10]. Table II presents the relative density in function of sintering temperature, ranging from 1200 °C to 1950 °C with a holding (sintering) time ranging from 5 to 30 min, under a fixed pressure of 77 MPa and a fixed heating rate of 700 °C/min.…”

Tailoring the microstructure and the mechanical properties of ultrafine grained high strength ferritic steels by powder metallurgy

“…SPS has been widely used because of its ability to heat up the material very quickly, providing a powerful tool to retain the original nanostructure [16e19]. For industrial purpose, it has been used for ceramics applications and refractory materials whereas only few studies were dedicated to metallic materials [20,21]. Ji et al [17,22] demonstrated that SPS can be used to retain the nanostructure of ODS intermetallic alloys.…”