Direct selective laser sintering of iron–graphite powder mixture

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

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.

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

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.

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.

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

Cranioplasty is the second procedure in the history of neurosurgery after trepanation, and it is still relevant despite the development of civilization and progress in medicine. Each cranioplasty operation is unique because there are no two patients with identical defects of the skull bones. The development of Direct Metal Laser Sintering (DMLS) technique opened up the possibility of direct implant printing of titanium, a biocompatible metal used in medicine. This eliminates the need for producing any intermediate products to create the desired implant. We have produced 8 patient-specific titanium implants using this technique for patients who underwent different decompressive cranioectomies associated with bone tumors. Follow-up duration ranged from 6 to 12 months. We observed no implant-related reactions or complications. In all cases of reconstructive neurosurgery we achieved good clinical and aesthetic results. The analysis of the literature and our own experience in three-dimensional modeling, prototyping, and printing suggests that direct laser sintering of titanium is the optimal method to produce biocompatible surgical implants.

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.

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.

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.

Features of obtaining bentonite-based ceramic support using SLS 3D printing

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.

Rapid Prototyping and Tooling (RP&T) technologies are applied extensively and intensively in the industry and their importance is increasing because it reduces the development time and cost required for product prototyping and injection moulding dies and EDM electrodes tooling. Namely additive technologies are getting interest due to the possibility to build a component by adding material. The paper addresses the study and application of Direct Metal Laser Sintering (DMLS) of copper alloys for Rapid Tooling of dies for thermoplastic polymer injection moulding. Specific samples have been designed by CAD, in order to be representative of the geometrical and morphological features and functional characteristics of the dies. The main limitations of DMLS prototypes are relevant to surface properties as porosity, roughness, hardness, corrosion, erosion and wear resistance. The study takes into consideration the characterization and improvement of DMLS surface properties in order to meet their functional requirements. To this purpose, different surface treatments have been studied and applied, as blasting and peening, resin infiltration, electroless nickel plating. Sample surfaces has been fully characterized and analysed, as obtained by DMLS, and after surface treatments. 3D surface roughness and microgeometrical morphology and porosity and microhardness properties have been systematically investigated.

Direct Metal Laser Sintering (DMLS) is a net shape fabrication technology that has been developed especially to fulfill the requirements of rapid tooling. The most important factors for successful rapid tooling are: 1) accuracy, 2) surface quality, 3) material properties and 4) speed. Surface quality has been the major concern for development work because rapid tooling applications require very smooth surfaces and finishing work is often needed. The quality of all surfaces can be greatly improved by reducing layer thickness and adjusting optimal scanning parameters in the DMLS process. Simultaneously stair-stepping effect can be minimized and almost faded out. Straightforward progress to smaller layer thickness has required material development work of finer metal powders and intensive research work for optimal laser processing. Simultaneously part building strategies have become more intelligent. It has been proved in practical cases that even 20 µm thin layers can be used for building steel parts with superior surface quality.This paper describes some of the key features for Direct Metal Laser Sintering of very fine metal powders. Latest results and experiences of research and development team at Rapid Product Innovations (formerly Electrolux Rapid Development) are discussed.Direct Metal Laser Sintering (DMLS) is a net shape fabrication technology that has been developed especially to fulfill the requirements of rapid tooling. The most important factors for successful rapid tooling are: 1) accuracy, 2) surface quality, 3) material properties and 4) speed. Surface quality has been the major concern for development work because rapid tooling applications require very smooth surfaces and finishing work is often needed. The quality of all surfaces can be greatly improved by reducing layer thickness and adjusting optimal scanning parameters in the DMLS process. Simultaneously stair-stepping effect can be minimized and almost faded out. Straightforward progress to smaller layer thickness has required material development work of finer metal powders and intensive research work for optimal laser processing. Simultaneously part building strategies have become more intelligent. It has been proved in practical cases that even 20 µm thin layers can be used for building steel parts with s...