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The purpose of this paper is to characterize polyamide parts prepared by the SLS process using techniques that are dependent on surface properties and compare the results to density measurements in order to assess which technique better reflects the degree of densification achieved using different laser power levels.

Fabrication of Nylon 12 (Duraform PA) samples and their characterization by apparent density measurements, perfilometry, Raman spectroscopy, scanning electron microscopy, specific surface area and contact angle measurements.

Methods dependent on surface analysis are not suitable indicators of the degree of sample densification. Among the surface methods, the results from Raman spectroscopy are the ones with the best performance. Incipient sintering of the superficial layers and raw material powder on the surface, inherent to the parts made by the SLS process, strongly interfere with the characterization.

Quantitative comparison of a number of surface probing methods for monitoring densification of SLS parts. Characterization of sample surfaces with and without raw material powder.

Presents a finite element formulation of hot isostatic pressing (HIP) based on a continuum approach using thermal‐elastoviscoplastic constitutive equations with compressibility. The formulation takes into consideration dependence of the viscoplastic part on the porosity. Also takes into account the thermomechanical response, including nonlinear effects in both the thermal and mechanical analyses. Implements the material model in an implicit finite element code. Presents experimental procedures for evaluating the inelastic behaviour of metal powders during densification and experimental data. Chooses the simulation of the dilatometer measurement of a cylindrical component during HIP and manufacturing simulation of a turbine component to near net shape (NNS) as a demonstrator example. Both components are made of a hot isostatically pressed hot‐working martensitic steel. Compares the result of the simulation in the form of the final geometry of the container with the geometry of a real component produced by HIP. Makes a comparison between the calculated and measured deformations during the HIP process for the cylindrical component. Measures the final geometry of the turbine component by means of a computer controlled measuring machine (CMM). Performs the complete process from design and simulation to geometry verification within a computer‐aided concurrent engineering (CACE) system.

Preparing CrAlN coatings on the surface of silicon nitride bearings can improve their service life in oil-free lubrication. This paper aims to match the optimal process parameters for preparing CrAlN coatings on silicon nitride surfaces, and reveal the microscopic mechanism of process parameter influence on coating wear resistance.

This study used molecular dynamics to analyze how process parameters affected the nucleation density, micromorphology, densification and internal stress of CrAlN coatings. An orthogonal test method was used to examine how deposition time, substrate temperature, nitrogen-argon flow rate and sputtering power impacted the wear resistance of CrAlN coatings under dry friction conditions.

Nucleation density, micromorphology, densification and internal stress have a significant influence on the surface morphology and wear resistance of CrAlN coatings. The process parameters for better wear resistance of the CrAlN coatings were at a deposition time of 120 min, a substrate temperature of 573 K, a nitrogen-argon flow rate of 1:1 and a sputtering power of 160 W.

Simulation analysis and experimental results of this paper can provide data to assist in setting process parameters for applying CrAlN coatings to silicon nitride bearings.

A three‐dimensional thermal finite element model including the effect of the powder‐to‐solid transition has been developed to investigate the transient temperature distribution and effects of substrate preheating during laser densification of dental powder bed for the layer‐by‐layer fabrication. The model encompasses the effects of the temperature‐ and porosity‐dependent thermal conduction and radiation as well as the temperature‐dependent natural convection. Substrate preheating is found to be important in preventing the formation of cracks in the dental porcelain body during laser densification. The simulation results are found to match the experiments very well.

Aluminum nitride (AlN) ceramics are suitable substrate and package materials for high-power integrated circuits.

Dense AlN ceramics with Y₂O₃ and LaF₃ as sintering additives are prepared. The effects of these additives on the density, phase composition, microstructure and thermal conductivity of AlN ceramics are investigated.

Results show that 2 Wt.% Y₂O₃-doped additive is insufficient for the samples to achieve the full densification sintered at 1,700°C. When LaF₃ is added with Y₂O₃, the samples are perfectly densified at the same sintering condition. The relative density and thermal conductivity of the samples are 97.8-99.07 per cent and 169.104-200.010 W·m-1·K-1, respectively. The density of the samples and their microstructure, especially the content and distribution of secondary phases, is necessary to control the thermal conductivity of AlN ceramics.

Y₂O₃ and LaF₃ additives can effectively promote densification and enhance the thermal conductivity of AlN ceramics in a low sintering temperature, and the AlN ceramics added with Y₂O₃-LaF₃ might have potential applications in package materials for high-power integrated circuits.

This work is focused on the investigation of direct production of electrical discharge machining (EDM) electrodes through the selective laser sintering (SLS) technique using a new metal-matrix composite material made of molybdenum and a copper-nickel alloy (Mo-CuNi). The influence and optimization of the main SLS parameters on the densification behavior and porosity is experimentally studied. Additionally, EDM experiments are performed to evaluate the electrodes performance under different machining conditions. The paper aims to discuss these issues.

The new EDM electrode material used was a powder system composed of Mo and pre-alloyed CuNi. A systematic experimental methodology was designed to evaluate the effects of layer thickness, laser scan speed and hatch distance. The 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 solid copper electrodes EDMachined under the same conditions.

The experimental results showed that the direct SLS manufacturing of composite electrodes is feasible and an adequate combination of parameters can produce parts with good quality. The laser scan speed has a great effect on the densification behavior of the samples, while the effect of hatch distance on the porosity is more visible when the overlapping degree is considered. The overlapping also had a significant effect on the surface morphology. The EDM results showed that the Mo-CuNi electrodes had superior performance to the copper powder electrodes made by SLS for all the EDM regimes applied, but inferior to those achieved with solid copper electrodes.

Significant results on the direct SLS manufacturing of a new 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 Mo-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.

The purpose of this paper is to examine the involvement of the concept of city identity in the design process of urban densification and outline how can today's urban projects be able to reinforce the delicate balance between conservation, development management and sustainability objectives.

Based on case study approach, this paper focus on “Park Mall and Four Point Hotel” project, located in the historic city centre of Setif (Algeria) and takes the procedure of designing as its conceptual framework. Following this, it explores genesis document of the project and assesses architect's choices attributed to six elements of architectural language. These elements are apprehended regarding their relevance, which depends on whether the new building is or not compatible/integrated with the existing environment, and how far does it reinvent the modern vision.

The paper provides empirical insight about how the concept of identity is used during the design process of densification project. It argues that this latter consists on a dynamic process shaped by cultural, socioeconomic and institutional specificities applying local/global design precedents, multifunctionality concept and novel features in a tourism-oriented mindset and to still maintain and improve the specific identity of the city centre, thus becoming an active way to reconcile conservation, sustainability and development management objectives.

This paper raises discussion on how the concept of city identity could renew the field of heritage conservation and development management. Therefore, it fulfils an identified need to study how can urban projects reconcile conservation, development management and sustainability objectives.

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.

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.

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.

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.

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.

The purpose of this paper is to compare different powder metallurgy (PM) processes to produce ceramic parts through additive manufacturing (AM). This creates the potential to rapidly shape ceramic parts with an almost unlimited shape freedom. In this paper, alumina (Al₂O₃) parts are produced, as Al₂O₃ is currently the most commonly used ceramic material for technical applications.

Variants of the following PM route, with indirect selective laser sintering (indirect SLS) as the AM shaping step, are explored to produce ceramic parts: powder synthesis, indirect SLS, binder removal and furnace sintering and alternative densification steps.

Freeform-shaped Al₂O₃ parts with densities up to approximately 90 per cent are obtained.

The resulting Al₂O₃ parts contain inter-agglomerate pores. To produce higher-quality ceramic parts through indirect SLS, these pores should be avoided or eliminated.

The research is innovative in many ways. First, composite powders are produced using different powder production methods, such as temperature-induced phase separation and dispersion polymerization. Second, four different binder materials are investigated: polyamide (nylon-12), polystyrene, polypropylene and a carnauba wax – low-density polyethylene combination. Further, to produce ceramic parts with increased density, the following densification techniques are investigated as additional steps of the PM process: laser remelting, isostatic pressing and infiltration.

This paper aims to better control the mechanical properties and functional properties of NiTi alloy.

NiTi alloy samples with equal atomic ratio were formed by selective laser melting (SLM). X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy and tensile testing methods were used to study the effects of different laser power and scanning speed on the densification behavior, phase transformation characteristics and mechanical properties of NiTi alloy.

Compared with the laser power, the variation of the keyhole effect caused by the change of scanning speed is more intense, which has a greater effect on the densification behavior of SLM NiTi alloy. The effect of the laser power on the phase transition temperature is small. The increase of scanning speed weakens the burning degree of Ni element, so phase transition temperature decreases. The results of DSC test and tensile test show that the scanning velocity can significantly change the phase transition temperature, martensite twins reorientation and stress–strain behavior of SLM NiTi alloy.

This study provides a potential method to regulate the mechanical properties and functional properties of NiTi shape memory alloy in the future and NiTi alloys formed by SLM with good elongation were obtained because the Supercellular crystal structure formed during the nonequilibrium solidification of SLM and the superfine precipitates dispersed in the alloy prevented the dislocation formation.