Consolidation by spark plasma sintering (SPS) of polyetheretherketone

Abstract

The present study deals with the consolidation of an ultra‐high performance polymer, the poly(ether ether ketone) (PEEK), for structural applications, using the powder metallurgy (PM) way, and more precisely the Spark Plasma Sintering (SPS) processing. The effects of SPS parameters such as temperature, pressure, and dwell time on density and mechanical properties of PEEK were investigated via a Design of Experiments (DoE). A temperature of 250 °C, a pressure of 40 MPa, and a dwell time of 20 min have been identified as the optimal SPS process parameters. In these conditions, a density of 1.31 g/cm3 was reached and homogeneous mechanical properties in the volume determined by means of compression tests were found with a compressive modulus of 2.75 GPa, a yield strength of 134 MPa, and a maximum compressive strain of 43%. These results are better than those of commercial products obtained by injection molding. The pressure appears to be a significant parameter on PEEK properties and plays positive or negative roles according to the responses of DoE studied. To our knowledge, it is one of the first studies based on the application of the PM techniques for PEEK consolidation showing the possibility to process below its melting point. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44911.

Effects of pressure on poly(ether‐ether‐ketone) (PEEK) sintering mechanisms

“…The same semicrystalline PEEK powder supplied by Solvay for the previous study was considered as the starting material. The particle size was in the range of 20–140 μm and a density of 1.31 × 10 3 kg m −3 was indicated by the supplier.…”

“…The powder was weighed to obtain cylindrical specimens 10 mm in thickness and 30 mm in diameter at full densification. Processing was carried out at a heating rate of 10 °C min −1 until the set temperature, following the procedure set up in a previous work to allow the even distribution of temperature in the sample. For the SPS experiments, the uniaxial loading was applied at a given temperature with a rate of 10 MPa min −1 (unless otherwise indicated) up to the desired pressure and was then held for the remaining sintering cycle.…”

“…In a previous study, Sébileau et al . demonstrated PEEK processability below the melting temperature by SPS in which pressure appears to be a parameter which strongly influences the mechanical properties of processed PEEK.…”

“…The proposed solutions are the use of unusual powder metallurgy methods like laser sintering for PEEK or, more recently, the process called “spark plasma sintering” (SPS). This is an unconventional technique and few authors have shown that PEEK pellets can be consolidated by SPS below the melting point while keeping mechanical properties similar to those achieved using standard techniques. Nevertheless, the origin of the remarkable mechanical properties observed without any complete melting of the polymer remains poorly understood.…”

“…In addition, very rapid processing of polymers has been reported . For instance, less than 30 min is required to produce thick thermoplastic sintered PEEK plates using the SPS technique …”