Cranioplasty with individual titanium implants

Influence of reinforcement weight fraction on microstructure and properties of submicron WC–Co p/Cu bulk MMCs prepared by direct laser sintering

Effects of dispersion technique and component ratio on densification and microstructure of multi-component Cu-based metal powder in direct laser sintering

Development and characterisation of direct laser sintering multicomponent Cu based metal powder

Additive manufacturing (AM) has experienced significant growth in recent years, emerging as a transformative technology with broad applications across various industries. This review explores the advantages, disadvantages, and environmental impacts of AM, an important area of consideration as this technology continues to gain popularity. By analyzing existing literature, we assess the challenges associated with AM processes, particularly in comparison to traditional manufacturing methods. AM has the greatest potential to contribute to sustainable development by the production of lightweight components and complex industrial products with intricate designs. These products are made with minimal material usage. Consequently, also waste and emissions are reduced, which are significant environmental advantages. Overall, this review highlights the importance of AM as a tool for advancing sustainability in manufacturing and offers valuable insights for Continuous Fiber Fabrication, Direct Metal Laser Sintering, and Selective Laser Sintering techniques to enhance their competitive advantage while reducing their environmental impact.

A direct selective laser sintering (SLS) process was combined with a laser preheating procedure to decrease the temperature gradient and thermal stress, which was demonstrated as a promising approach for additive manufacturing of BaTiO 3 ceramics. The phase compositions in BaTiO 3 ceramics fabricated by SLS were investigated by X‐ray and neutron diffractions. The surface morphologies and cross‐section microstructures were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A dense hexagonal h‐BaTiO 3 layer was formed on the surface and extended to a depth of 500 μm, with a relative density higher than 97% and absence of pores or microcracks. SLS resulted in the formation of the high‐temperature phase, h‐BaTiO 3 , which was retained at room temperature possibly due to the high cooling rate. The grain boundaries of SLSed h‐BaTiO 3 ceramics consist of a Ti‐rich secondary phase. Compared with that of the pressureless sintered t‐BaTiO 3 ceramics, the Vickers hardness of SLSed h‐BaTiO 3 is 70% higher.

This paper focuses on the improvement of ultrasonic defectoscopy used for machine elements produced by direct laser metal sintering. The direct laser metal sintering process introduces the mixed metal powder and performs its subsequent laser consolidation in a single production step. Mechanical elements manufactured by laser sintering often contain many hollow cells due to weight reduction. The popular pulse echo defectoscopy method employing very high frequencies of several GHz is not successful on these samples. The aim of this paper is to present quadraphonic transmission ultrasound defectoscopy which uses low range frequencies of few tens of kHz. Therefore, the advantage of this method is that it enables defectoscopy for honeycombed materials manufactured by direct laser sintering. This paper presents the results of testing performed on AlSi12 sample.

Balling phenomena in direct laser sintering of stainless steel powder: Metallurgical mechanisms and control methods

PurposeTo identify the effects of laser scan speed and scan spacing on surface morphology, microstructure and structure evolution in direct laser sintering of Cu‐based metal powder.Design/methodology/approachScanning electron microscope, differential thermal analyser (DTA) and X‐ray diffractometer were used to examine the microstructure of the sintered parts.FindingsIt was found that the decrease of the scan speed and scan spacing could lead to densification due to solute‐reprecipitation mechanism. The formation of oxide Cu2O is sensitive to the scan spacing due to the lack of Cu3P protection under the re‐heating condition if using small scan spacing. Furthermore, the result shows that there exist two mechanisms in determining the phosphor distribution. During the laser sintering, concentration diffusion acts as the main mechanism at a fast scan speed and a large scan spacing while solute‐reprecipitation acts as the main mechanism at a low scan speed and small scan spacing.Originality/valueThis paper discloses the influence of process parameters on microstructure evolution and the mechanism of densification in direct laser sintering Cu‐based metal powder. It offers practical help to the researchers who are interested in direct laser sintering metal powder.

Nanostructured ceramic bulk materials were achieved from nano-Al2O3 ceramic powders via direct selective laser sintering (SLS). SLS as a non-traditional machining technology of Rapid Prototyping was introduced and compared with other ceramic forming technologies. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were applied to analyze the microstructure of the ceramic bulk materials. These results demonstrated that the nano-Al2O3 ceramic powders can be sintered into bulk materials maintained nanostructure with some technological parameters. It was found that the nanostructured ceramic bulk exhibited unique microstructure and was free formed rapidly by this sintering technology.

This study was conducted to comparatively assess the retention and vertical marginal fit of cobalt-chromium copings fabricated by the conventional casting technique, 3D-printed resin pattern, and with direct metal laser sintering (DMLS) technique. Out of the total 60 test samples, 20 copings were obtained from inlay-casting wax and 20 from casting of 3D-printed resin patterns. In total, 20 copings were obtained from the laser sintering technique. All 60 test samples were then cemented serially on the prepared maxillary-extracted premolars and were evaluated for vertical marginal gap in 8 pre-established reference areas. Retention was evaluated using a universal testing machine. Results obtained for both marginal gap and retention were statistically analyzed, and the values fall within the clinically acceptable range. The DMLS technique proved precedence over the other two techniques used, as it exhibited maximum retention and marginal accuracy, which is an area of prime concern. The results from this study encourage further research with different pattern-forming materials and techniques and the need to identify the factors that facilitate better marginal fit and retention of cast restorations. This study has myriad of applications in clinical dentistry mainly in decision-making for casting procedure to provide better retention and marginal accuracy for fabrication of Co-Cr crowns. It also aims to aid the clinician to minimize errors by using different techniques for fabrication of wax pattern as well as the coping, keeping abreast with the recent technology to evaluate the accuracy of 3D-printed resin pattern over conventional wax pattern.

ABSTRACTWe demonstrate a laser direct-write method, a maskless process that transfers material directly from a ribbon to a substrate. This process offers the promise of fabricating passive electronic micro-components at a high speed with high spatial resolution. We are developing a workstation implementing this direct-write method, which integrates deposition, direct laser sintering, and micromachining capability on a single machine. Using this workstation we have deposited micro-patterns of conducting lines and resistors on alumina and polyimide substrates under ambient conditions that exhibit good electrical properties and substrate adhesion. From preliminary studies of laser sintering it was found that a wide range of sintering conditions may be used to arrive at silver conducting lines (∼60 µm × 10 µm) on alumina substrate with resistivity in the range of 5 to 10 times the resistivity of bulk silver. Preliminary results also indicate direct laser sintering of cermet resistor material can yield reproducible resistance values.

Direct selective laser sintering (DSLS) of silicon carbide (SiC) ceramics enables the rapid fabrication of complex shaped porous SiC ceramics, making it a promising additive manufacturing technology for SiC materials. However, due to the inability of SiC to maintain a stable liquid phase, challenges arise in solid state sintering via laser, including slow diffusion rates and poor bonding strength in the resulting SiC ceramics. This study investigates the effect of Al2O3‒Y2O3 liquid‐phase sintering additives on the porosity, microstructure, and physical properties of sintered bodies under different energy densities. The results show that by adjusting the energy density during the DSLS process (5.5‒13.9 J mm−2), porous SiC ceramics with porosities ranging from 45.57% to 56.91% can be produced. As the energy density increases from 5.5 to 13.9 J mm−2, the compressive strength, thermal conductivity, resistivity, and specific compressive strength range from 25.00 to 181.80 MPa, 6.12 to 15.66 W m−1 K−1, 4.17 to 34.58 Ω cm, and 17 to 97 MPa cm3 g−1, respectively. This study reveals the microstructural evolution and changes in the physical properties of DSLS‒SiC under the influence of Al2O3‒Y2O3 liquid‐phase sintering additives.

The Effect of Post-processing and Machining Process Parameters on Properties of Stainless Steel PH1 Product Produced by Direct Metal Laser Sintering

ABSTRACTThis research relates to the design, modelling and fabrication of 3D metal printed heat sinks. The heat sinks presented in the research are the commonly used longitudinal fin solid heat sink (LFSHS) and three LFSHS lattice structure designs, differing only in their lattice sizes, fabricated using the Direct Metal Laser Sintering (DMLS) technique in Maraging Steel (MS1), on an EOSINT M280 system. In order to increase the heat sink surface area, the heat sinks are manufactured with mesh lattices along the length of the fins, while keeping the overall heat sink volume constant. The research is focused on pushing the limitations of the DMLS technique for the development of repeating unit, lattice structures heat sinks, and to examine the effect of incrementally varying the lattice sizes with regards to the resultant surface area of the heat sink and the thermal performance of the system. The results obtained under natural convection show that the thermal performance of the LFSHS outperformed all lattice structure heat sinks. This is due to the fact that, the pressure drop across the lattice heat sinks were so high, due to lattice meshes that it negated the positive effect of the greater surface area.

Purpose – This work aims to investigate the direct production of electrical discharge machining (EDM) electrodes by means of the selective laser sintering (SLS) technique using a new non-conventional metal-matrix composite material (TiB2-CuNi). The influence and optimization of the main SLS parameters on the densification behavior and porosity is experimentally studied. EDM experiments are also performed to evaluate the electrodes performance. Design/methodology/approach – The new EDM electrode material used was a powder system composed of TiB2 and CuNi. Making use of a designed systematic experimental methodology, the effects of layer thickness, laser scan speed and scan line spacing were optimized, where aspects such as densification behavior, porosity and surface morphology of the samples were analyzed through microstructural and surface analysis. EDM experiments were conducted under three different regimes in order to observe the electrodes behavior and performance. The results were compared with copper powder electrodes manufactured by SLS and EDMachined under the same conditions. Findings – The experimental results showed that the direct SLS manufacturing of composite electrodes is feasible and promising. The laser scan speed has a high effect on the densification behavior of the samples, while the effect of scan line spacing on the porosity is more visible when the overlapping degree is considered. Surface morphology was not affected by the scan line spacing, whereas balling phenomenon was reported, regardless of the scan line spacing. The EDM results showed that the TiB2-CuNi electrodes had a much superior performance than the copper powder electrodes made by SLS, regardless of the EDM regime applied. Research limitations/implications – Generally, the machine tool itself promotes some restrictions to the SLS process optimization. It is normally attributed to the characteristics of the laser type and the amount of energy that can be delivered to the powder bed. The present investigation could not cover all the optimization potential involved with the studied material due to limitations of the SLS machine tool used. Originality/value – Significant results on the direct SLS manufacturing of a new non-conventional composite material, which has a great technological potential to be used as an EDM electrode material, are presented. Valuable guidelines are given in regard to the SLS optimization of TiB2-CuNi material and its performance as an EDM electrode. This work also provides a systematic methodology designed to be applied to the SLS process to produce EDM electrodes.