Polymer Materials Reinforced with Silicon Nitride Particles for 3D Printing

Abstract

Comprehensive research into the production of a ceramic-reinforced polymer material from highdensity polyethylene or polypropylene and β-Si3N4 powder was conducted. The incorporation of silicon nitride ceramic particles (5 and 10 vol.%) into the polymers to make polymer–ceramic filaments was studied step by step. High-quality polypropylene–ceramic filaments could be obtained at an extrusion temperature of 150°C with an extrusion speed of 20 cm/min and polyethylene–ceramic filaments at 160°C and 30 cm/min. Data on the shape and size distribution of Si3N4 particles were used to simulate the elementary volume of the filaments to determine the mechanical properties of the composites applying a 2D finite-element model. The reinforcement of the polypropylene/polyethylene-matrix material by 10 vol.% Si3N4 particles was not sufficient because the composite elastic modulus increased insignificantly and the critical strain decreased substantially to incorporate a greater volume of hard particles to improve the elastic modulus. To assess the quality of the polymer–ceramic filaments, parts of different shape (washer and auger) from reinforced and unreinforced filaments were designed and printed. The printed polymer–ceramic parts demonstrated a smooth surface and had no ledges or discontinuous areas. The mechanical (Vickers and Brinell hardness) and tribological (volume wear) properties of the materials were examined. Wear tests of the polyethylene–Si3N4 composite showed that its wear resistance tended to improve with increasing ceramic content of the filament. The low abrasive wear of the Si3N4-reinforced polypropylene/polyethylene material and the behavior of ceramic particles in contact with the indenter indicate that the composite has high fracture resistance in 3D printing.