Effect of Dendritic Copper Powder Addition to Polyamide 12 in Selective Laser Sintering

Günümüzde polimer malzemeler ev eşyalarından mühendislik uygulamalarına kadar geniş bir kullanım alanına sahiptir. Bu nedenle özelliklerinin geliştirilmesi önemlidir. Katkı maddeleri ilavesi, polimer malzemelerin özelliklerini artırabilmektedir. Katkı ilave tekniği ve bileşimleri imalat yöntemine göre değişebilmektedir. Yeni bir üretim yöntemi olup kızılötesi lazer ışını ile polimer tozlarının sinterlenmesine dayanan Seçici Lazer Sinterleme (SLS) toz yataklı eklemeli imalat metodunda da katkı maddelerinin kullanılması mümkündür. Bu metotta katkı kullanımı çok yaygın olmasa da en çok tercih edilen katkı maddeleri seramik esaslı inorganik malzemelerdir. Bununla birlikte, ince metalik parçacıklar da katkı maddesi olarak kullanılabilir. Bu çalışmada dendritik bakır tozu katkılı poliamid 12'nin SLS ile prosesi incelenmiştir. İki farklı katkı içeriğindeki toz karışımları proses parametreleri belirlemek amacıyla karakterize edilmiş ve artan enerji yoğunluğunun kullanılması gerektiği saptanmıştır. Beş farklı parametre kullanılarak üretilen numunelerin fiziksel ve mekanik testleri sonucu katkı ilavesiyle eğme özellikleri ve boyutsal hassasiyet düşerken, yüzey pürüzlülüğü değişmemiş ve depolama modülü iyileşme göstermiştir.Today, polymer materials have a wide range of usage areas that are from household goods to engineering applications. Therefore, improvements in their properties are essential. The addition of fillers can increase the properties of polymer materials. Filler addition techniques and compositions can vary with the manufacturing methods. It is also possible to use fillers in selective laser sintering (SLS) powder bed fusion additive manufacturing method, which is a new manufacturing method based on the sintering of polymer powders with an infrared laser beam. Although the use of fillers is not very common in this method, the most preferred fillers are ceramic based inorganic materials. However, fine metallic particles could also be used as fillers. This study investigates the processing of dendritic copper powder filled polyamide 12 by SLS method. Powder mixtures in two different filler contents were characterized to determine process parameters, and it was determined that increased energy density should be used. As a result of the physical and mechanical tests of the sintered samples produced using five different parameters, the bending properties and dimensional sensitivity decreased with the filler addition, while surface roughness did not change, and the storage modulus improved

Investigation of Wear Behavior of PA 12 Matrix Ceramic Reinforced Composites Produced by Selective Laser Sintering Method

In this study, ceramic-reinforced PA 12 matrix composites were fabricated by using Selective Laser Sintering (SLS) additive manufacturing method with different energy density values. Additionally, dry sliding wear tests were performed at 25 mm/sec and 100 mm/sec velocity values and at 5 N and 20 N wear load values. In conclusion with the tests, it was found that when energy density increases the wear rate increases. The wear rate values are given in Table A

A PCE-based rheology modifier allows machining of solid cast green bodies of alumina

The performance of a poly(carboxylate ether) (PCE)-based superplasticizer to enable the machining of green bodies that are solid cast from suspensions of alumina was investigated. An alumina loading of 35 vol% in the presence of 1.25 wt% superplasticizer was established to be suitable for lathing and removal of significant amount of material through drilling. A reduction of 77% in the diameter of green bodies that corresponds to a 59% reduction in volume was achieved. The lathed green bodies exhibited smooth terraces without visible cracks. All of the green bodies were sintered without a polymer burnout step

Processing and Characterization of Hollow Glass-Filled Polyamide 12 Composites by Selective Laser Sintering Method

Selective Laser Sintering (SLS) is an accepted and improving technique for additive manufacturing in many different areas, from the applications of aerospace to automotive, consumer products to dental and medical materials. Lightweighting is a significant issue, especially in terms of the automotive and aerospace industries, mainly to increase fuel efficiency and reduce CO2 emission. The density reduction can be obtained by the addition of Hollow Glass Microspheres (HGMs) to Polyamide 12 (PA 12) polymer matrix. This study covers the different amounts of HGM filled PA 12 productions by SLS method and final structure characterization of PA 12-HGM composites. According to the performing thermal, physical, and mechanical tests, on increasing the amount of HGM in the structure, 10, 15, 20 weight percentages, respectively, the density of composites has been reduced significantly up to 20% for 20% of HGM filled PA 12 (PA 12–20HGM) composite, besides having a substantial rise in E-modulus

Thermoplastic Polymers and Polymer Composites Used in Selective Laser Sintering (SLS) Method

Selective laser sintering (SLS) is a powder bed fusion (PBF) additive manufacturing (AM) technique that uses high-energy beams (laser beams, electron beams, or an infrared panel heater) to coalescence (or melt) polymer particles by a layer-by-layer procedure to create 3D solid models. This chapter describes the types of thermoplastic polymers and thermoplastic polymer composites, which are currently used and available in SLS-AM method, and their specific details in terms of materials and materials preparation for Laser Sintering (LS) process, which include physical, mechanical, and microstructural aspects. The most commonly used thermoplastic polymers in this method are polyamides (mainly Polyamide 12, followed by Polyamide 11, Polyamide 6), and non-polyamide polymers like polyolefins (Polypropylene, Polyethylene), Polyetheretherketone, thermoplastic urethane. In this section, the polymer composites that can be produced via SLS method, and the type of additives that are used to create polymer composites such as glass beads, glass fibers, carbon fibers, carbon black, silicon carbide, aluminum powder, nano-silica, nano-clay, nano-Al2O3 have also been discussed. The production of polymer composite structures with SLS-AM method, and developing the interface compatibility properties of the additives with the polymers are among the current issues in this area. Therefore, as the currently used and well-known commercial products, this section covers material developments in SLS method, the novel type of polymers, additives, and polymeric composites, and preparation characteristics of polymer composites and blends

Electrochemical Corrosion Behaviour of UNS S32205 Duplex Stainless Steel Dependent on Sigma Phase Precipitation

In this study, the microstructure and electrochemical corrosion behavior of the UNS S32205 alloy were investigated. Firstly, the phase diagram of the studied samples was determined by Thermo-Calc 2022 software, and the solution treatment temperature was designated. The studied samples were cooled by various cooling rates following the solution treatment at 1050 °C for 30 min. The samples were characterized by optical microscope, scanning electron microscope, and XRD analysis. Also, electrochemical corrosion behavior was investigated by potentiodynamic polarization, cyclic potentiodynamic polarization and electrochemical impedance spectroscopy analyses. Microstructural examinations revealed that decreasing cooling rate causes the precipitation of the sigma phase, and the ratio of the sigma phase was increased up to 29 % by the decreasing cooling rate. Furthermore, it was determined that precipitation of the sigma phase reduces the Epit values, and the sample with the highest amount of sigma exhibits the lowest corrosion resistance. On the other hand, presence of the sigma changed the electrochemical impedance spectroscopy behavior of the UNS S32205 and double-layered model fit the results

Selective Laser Sintering Manufacturing and Characterization of Lightweight PA 12 Polymer Composites with Different Hollow Microsphere Additives

The use of additives in polyamide polymeric SLS built frameworks further reinforces the goal of developing lightweight components, which serves as the basis for the current investigation. In this paper, different amounts of hollow glass microspheres (HGMs) were added to polyamide 12 (PA 12), and their sintered components were compared for their physical and mechanical properties, including tensile and 3-point bending tests. In terms of density reduction, the PA 12-20HGM composite structure achieved the highest reduction figure of 20.8 %. According to specific strength and modulus calculations, PA 12-20HGS60 and PA 12-20HGM composite structures provided the highest mechanical test results

Dry Sliding Wear Behavior of Energy Density Dependent PA 12/Cu Composites Produced by Selective Laser Sintering

The selective laser sintering process is widely used to fabricate polyamide matrix composites. Although various reinforcements are used to produce polyamide matrix composites, metallic-based reinforcements are used to improve the mechanical properties of the structure. Also, selective laser sintering process parameters significantly affect the microstructural and mechanical properties of the composite products. In this study, polyamide 12 (PA 12) matrix composites were produced with Cu particulates by selective laser sintering methods using various energy density values. Moreover, dry sliding wear of the energy density dependent PA 12/Cu composites was investigated. Worn samples were characterized by scanning electron microscopy and 2D profile analysis. The examinations revealed that the lower energy density values improve the microstructural properties and wear behavior of the PA 12/Cu composites. It was obtained that the lowest energy value provides the highest wear resistance for the PA 12/Cu composites

Effects of Copper Fillers on Mechanical and Electrical Properties of Selective Laser Sintered PA 12-Cu Composites

Selective Laser Sintering (SLS) is a widely used additive manufacturing (AM) technique for creating 3D geometries by adding materials in layers. Although neat polymer is mainly used in powder forms for production, organic or inorganic fillers can be added to produce polymer composites by SLS method. In this study, Polyamide 12 (PA 12) matrix composite parts filled with two different copper particles, dendritic and spherical shaped, were produced, and their mechanical, structural and electrical properties were investigated. The present study outlined that by increasing incident energy densities during sample fabrication, changes in mechanical and electrical characteristics were examined. The findings were analysed in terms of filler type and energy input, which were discovered to have a slight change in the bending behaviour of SLS components. Furthermore, the impact strength was shown to increase constantly with increasing energy density. Furthermore, whereas the electrical conductivity of spherical Cufilled parts rose considerably, no significant change was seen in dendritic-shaped Cu-filled parts

Estimation of Surface Roughness in Selective Laser Sintering Using Computational Models

This study presents a comprehensive experimental dataset and a novel classification model based on Deep Neural Networks to estimate surface roughness for additive manufacturing. Many problems exist due to the very complex nature of the production process. Some focus on the production planning phase, including the nesting problem under many constraints. However, it is not possible to solve the main function without a clear understanding of the nature of the constraints. The purpose of this research is to present a method to automate the surface roughness estimation process in the production planning phase. The significance of this study is to implement a data-driven model for one of the most critical decision constraints in the nesting process. Solving this problem will automate a key decision constraint, and it might be implemented as an automated constraint module in solving the nesting problem. The proposed model focused on selective laser sintering (SLS) technology based on polyamide 12 powder applications. A comprehensive dataset is designed to simulate the behaviour of an industrial SLS manufacturing process based on a 3D positioning strategy. A set of samples with random positions are also created to test present the model’s robustness. The proposed classification model is based on Deep Neural Networks (DNN) with hyper-parameters designed for the problem. The dataset and the model provide a new user interface to estimate the surface roughness depending on the coordinates of a given product surface in an SLS production chamber and the production parameters employed in the production planning phase. The results show that the model can classify sample surfaces as “rough” or “smooth” with a very high percentage (95.8%) for the training set and with 100% for the test set. Benchmark results also show that the model outperforms other machine learning methods in classifying the surface roughness successfully on the test set