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As a kind of high performance polymer with excellent mechanical strength, high temperature property and chemical resistance, the polyether-ether-ketone (PEEK) and its composites are the promising candidates that can satisfy the demands for high stiff and lightweight in aerospace industry. So it is very attractive to fabricate PEEK and its composites parts with additive manufacturing technology, especially the selective laser sintering (SLS), due to its advantage on the fabrication of the parts with complex geometries. However, the strengths of the PEEK and its composites prepared by SLS are obviously lower than their injection molded parts and the laser sintering kinetics of the PEEK composites is seldom studied. In this paper, to fabricate the carbon fibers (CF) reinforced PEEK composites with high strength by SLS, the sintering kinetics of CF/PEEK composites was thoroughly studied based on the high temperature rheological behavior. A novel effective melting zone was defined by combining the simulated temperature distribution with the viscosity-temperature relationship and used to predict the process planning. Finally, the calculation results were validated by employing the simulation parameters in experiments and the tensile strength of CF/PEEK composites reached 109 ± 1 MPa with an elasticity modulus of 7365 ± 468 MPa, which is 85% higher than injection molded pure PEEK. Therefore, methods in this work could be considered as a complement to the numerical analysis of SLS process and the reinforced CF/PEEK composites may be used in aerospace industry for the structure optimization and lightweight design with complex geometries. [ABSTRACT FROM AUTHOR]

With the increasing research into selective laser sintering of composite powders, a modified numerical model was introduced to provide appropriate process predictions for the production of different functional composites. This numerical method included an effective volumetric heat source model and an integrated testing procedure, in which the differences of polyamide/carbon fiber (PA/CF) and PA/NaCl composite powders in thermo-physical and optical properties were studied. The unknown variables in the numerical model were all determined by experiments. The simulated temperature distributions of different powder beds exhibited a big difference in the melting depth. Entirely different processing parameters were planned for the two composites according to their simulation results. In the following experiments, highly porous PA derived from PA/NaCl composites had a maximum porosity of 59%. Compared with pure PA, CF reinforced PA showed a dramatic increase of the flexural strength and modulus by a factor of 100% and 380%, respectively. Therefore, the design objectives of two PA composites were both well accomplished. In addition, the experimental investigation became more efficient due to the process prediction. The accuracy of the model was validated by the microstructures of PA/CF and PA/NaCl, which meant this method could be used to provide appropriate process planning for more composites. [ABSTRACT FROM AUTHOR]

A novel method to design and manufacture hierarchically porous materials is proposed by combining Selective Laser Sintering (SLS) with particulate leaching technique. Hierarchically structural porous nylon is prepared and pore forming mechanism is discussed. Experimental results show that the porous materials contain the pores caused by the dissolution of the pore-forming agent in water and the pores existing inherently in SLS parts, which can be further divided into intraformational pores and interlaminar pores. The interactions of these pores with different shapes eventually form hierarchically porous nylon with high connectivity and controllable porosity. The influences of processing parameters and content of pore-forming agent on the porosity and water permeability have been studied. Porous nylon filter integrated with complicated structure is designed and directly fabricated by SLS. The fluid infiltration volume is tested and compared with commercially available water purifiers. The results of filtration experiment show that the filtering precision is about 17.6 μm and the rejection is up to 95% for the suspension containing particles with the size range of 15 μm–120 μm. [ABSTRACT FROM AUTHOR]

A novel method to prepare porous resin mould for pressure slip casting was proposed by using Selective Laser Sintering (SLS), which is one of Additive Manufacturing (AM) processes. The mixture of polyamide and salt (NaCl) were designed as raw materials, in which polyamide acted as matrix material and NaCl as pore-foaming agent. To investigate the feasibility of the pressure slip casting with the mould, the compressive strength and porosity of the porous specimens were measured. Experiments showed a compressive strength of 7.19 MPa and an elastic modulus of 32.26 MPa were reached. Meanwhile, the porosity of the specimens was 59.75%, and the aperture concentrated in 25–75 μm. The water permeability was verified and the maximum permeability reached to 0.921 mL/(mm 2 ·s). Pressure slip casting with porcelain slurry was performed using SLS porous specimens as the mould. Results showed the moisture content of the green body was about 23% and the relative density was 68.4%–74.1%. At last, a green body of whiteware with complex surface was prepared by the proposed method to demonstrate the feasibility of pressure slip casting with this mould. This method could be used in porcelain industry to realize rapid development of new products and customized production with further improvements. [ABSTRACT FROM AUTHOR]

Selective Laser Sintering (SLS) is one of the advanced additive manufacturing technologies which can build the geometrically complex structure from a three-dimensional CAD model. Poly ether ether ketone (PEEK) is one of the available materials for SLS and has received numerous interesting due to its excellent properties. In this research, a novel approach, thermally induced phase separation (TIPS) was employed to produce neat PEEK and PEEK/CNT composite powders with near spherical shape, desired particle size and size distribution for SLS application. Powders produced by TIPS demonstrated good flowability and processability. SEM images proved that CNT was embedded in PEEK powder. PEEK/CNT composite powder had shown an increased crystallinity in comparison with neat PEEK powder. Sintering rate of produced powders were studied with hot stage microscopy. Single layer films were built successfully by high temperature selective laser sintering (HT-SLS) using the powder developed via TIPS. Thermodynamics characteristics of single layer films were studied by DMA. Results revealed that addition of 0.1% CNT improved both storage and loss modulus of PEEK. PEEK powder is prepared by TIPS and laser sintered into 3D component by HT-SLS Unlabelled Image • The first study on preparation of PEEK and PEEK/CNT composite powders by TIPS. • Resulting powders have near spherical shape and preferred particle size for SLS application. • Resulting powders have shown good flowability and processability. • Powders have been successfully sintered into single layer films in the HT-SLS system. [ABSTRACT FROM AUTHOR]