Selective Laser Melting of Diamond-Containing or Postnitrided Materials Intended for Impact-Abrasive Conditions: Experimental and Analytical Study

Abstract

Materials with higher wear resistance are required in various applications including cutting elements (drag bits) of soft ground tunnel boring machines (TBM) to increase the productivity and to reduce the risk for workers involved in exchange operations (dangerous hyperbolic conditions). In recent work, two types of materials were produced by combining 3D printing (selective laser melting, SLM) of cellular lattice structures and spark plasma sintering (SPS) methods. The lattices were printed from (1) 316L stainless steel with diamond and (2) Ti6Al4V with nitriding. The effect of diamond content (5%, 10%, and 20%; nickel-coated particles) and unit cell size on performance was studied. The titanium alloy lattice was nitrided to increase its hardness and wear resistance. The effect of nitriding temperature (750°C, 900°C, and 1050°C) and lattice volume fraction (6%, 15%, and 24%, vol.) was investigated, and the optimized conditions were applied. The lattices were filled with 316L and Ti6Al4V powders, respectively, and consolidated by SPS. Samples were tested with the help of laboratory impact-abrasive tribodevice. Laboratory results have shown that both reinforcing approaches are beneficial and allow improvement of wear resistance in impact-abrasive conditions with great potential for TBM or similar applications. Modelling with the help of finite element method has shown that lattice structure enables reduction of peak local stresses in scratching and impact conditions.

The Impact Resistance of Highly Densified Metal Alloys Manufactured from Gas-Atomized Pre-Alloyed Powders

“…If energy is spent on (1) plastic, (2) elastic deformation, or (3) fracture of material, then the acceleration will be lower. The implemented test method can be used for a wide range of material types, such as ceramics or bioceramics, metal alloys, hard materials, and hybrid composites produced by SPS and/or SLM or other methods as additional characterization criteria [28][29][30][31]. The size of the indent can be used as an indication of "dynamic hardness."…”

Mechanical Behavior of Ti6Al4V Scaffolds Filled with CaSiO3 for Implant Applications

“…Hence, for the rectangular structure, stress concentration and distortion can appear in the upper part of sample, but honeycomb failure started from the bottom of structures. Adding metallic lattice structure (Ti6Al4V) to ceramic reinforcement like wollastonite (CaSiO 3 ) produces a composite with higher wear resistance, damage tolerance and mechanical properties resulting in a higher durability of bones [38,39]. The strut diameter of the lattice is currently ≈ 200 µm, while it could be increased up to 1 mm ( Figure 9C).…”

“…Weight Before Test (g) ( resistance, damage tolerance and mechanical properties resulting in a higher durability of bones [38,39]. The strut diameter of the lattice is currently ≈ 200 μm, while it could be increased up to 1 mm ( Figure 9C).…”

Comparison of Mechanical and Antibacterial Properties of TiO2/Ag Ceramics and Ti6Al4V-TiO2/Ag Composite Materials Using Combined SLM-SPS Techniques

“…The compressive test result of TiO 2 ceramic and Ti6Al4V-TiO 2 lattice composite was captured ( Figure 10) and showed the benefits of lattice structure perfectly. Finite element analysis prepares an estimation of metal-ceramic composite materials strength produced by combining SLM-SPS technique subjected impact, abrasion or compression loading [15][16][17]. Numerical simulation illustrated that fracture will occur at around 500 MPa for pure ceramic, while buckling for metallic lattice will start from 1200 MPa (Figure 11).…”