Fabrication and assessment of mechanical properties of open cell porous regular interconnected metallic structure through rapid manufacturing route

2018 ◽  
Vol 24 (1) ◽  
pp. 138-149 ◽  
Author(s):  
Jatender Pal Singh ◽  
Pulak Mohan Pandey
Keyword(s):  
Mechanical Properties ◽  
Computer Aided Design ◽  
Ceramic Powder ◽  
Pressureless Sintering ◽  
Sintering Process ◽  
Metallic Structure ◽  
Porosity Level ◽  
Open Cell ◽  
Content Type ◽  
Interconnected Porosity

Purpose The requirements of open cell porous regular interconnected metallic structure (OCPRIMS) in applications such as heat exchangers, sound absorption, fluid flow control, spark arresters and biocompatible inserts have been increased. As per available technology in the present scenario, only the metallic-based rapid prototyping (RP) machines can guarantee fabrication of OCPRIMS. Metal-based RP machines are capital-intensive. So, this study aims to develop a technique for fabrication of OCPRIMS economically using three-dimensional printing (3 DP) and pressureless sintering. Design/methodology/approach Three computer-aided design (CAD) models of varying designed interconnected porosity 73, 70 and 60 per cent were modeled to target metallic porosity 27, 30 and 40 per cent. The same were fabricated with ceramic-based powder using 3 DP. Thereafter, spherical bronze powder with average size of 200 µm was filled and sintered in pressureless manner under inert atmosphere of argon. After sintering, the specimens were cleaned with the help of pricking needles and high-pressure water. It flushed the burnt ceramic powder and allowed metallic portion to remain intact. The obtained specimens were inverse of CAD/3 DP models. The dimensional measurement at different stages of fabrication was carried out to find shrinkage. Sintered density and interconnected porosity were measured using Archimedes’ principle. The characterization of the fabricated specimens was done with the help of microstructure analysis, scanning electron microscopy and energy dispersive x-ray analysis. Mechanical properties were assessed using compressive, tensile and Charpy tests. Findings The feasibility has been explored successfully to fabricate OCPRIMS of phosphor bronze using 3 DP and pressureless sintering process. Interconnected porosity of 51.45, 56.45, 64.09 per cent of final metallic specimens has been observed against the targeted 27, 30 and 40 per cent. The increase in pore dimensions up to 19.13 per cent and shrinkage up to 5.44 per cent of outer dimensions were found to be the main causes of increase in interconnected porosity level. The characterization results exhibit the behavior of pressureless sintering process and stability of the fabricated specimens. Mechanical properties of fabricated structures are found to be dependent on porosity and strut diameter. Compressive and tensile strength decrease with the increase in porosity for strut diameter less than 1 mm, whereas they increase with the increase in strut diameter of 1 mm or more. A similar trend has been observed for impact strength also. Originality/value This paper explores the feasibility to fabricate OCPRIMS economically using 3 DP and pressureless sintering process.

scholarly journals Improvement of mechanical properties of HfB2-based composites by incorporating in situ SiC reinforcement through pressureless sintering

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
S. Ghadami ◽  
E. Taheri-Nassaj ◽  
H. R. Baharvandi ◽  
F. Ghadami
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Relative Density ◽  
Pressureless Sintering ◽  
Sintering Process ◽  
Vacuum Atmosphere ◽  
Sic Reinforcement ◽  
Microstructural Studies ◽  
Composite Samples

AbstractHfB2, Si, and activated carbon powders were selected to fabricate 0–30 vol% SiC reinforced HfB2-based composite. Pressureless sintering process was performed at 2050 °C for 4 h under a vacuum atmosphere. Microstructural studies revealed that in situ SiC reinforcement was formed and distributed in the composite according to the following reaction: Si + C = SiC. A maximum relative density of 98% was measured for the 20 vol% SiC containing HfB2 composite. Mechanical investigations showed that the hardness and the fracture toughness of these composites were increased and reached up to 21.2 GPa for HfB2-30 vol% SiC and 4.9 MPa.m1/2 for HfB2-20 vol% SiC, respectively. Results showed that alpha-SiC reinforcements were created jagged, irregular, and elongated in shape which were in situ formed between HfB2 grains and filled the porosities. Formation of alpha-SiC contributed to improving the relative density and mechanical properties of the composite samples. By increasing SiC content, an enhanced trend of thermal conductivity was observed as well as a reduced trend for electrical conductivity.

scholarly journals Effect of Magnesia on Zinc Oxide Stabilized Nano Alumina Ceramic Powder in Sintering Process and its Impact on Mechanical Properties

2013 ◽  
Vol 68 ◽  
pp. 723-729 ◽  
Author(s):  
T. Alam ◽  
K.H.A. Al Mahmud ◽  
M.F. Hasan ◽  
S.A. Shahir ◽  
H.H. Masjuki ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Zinc Oxide ◽  
Ceramic Powder ◽  
Alumina Ceramic ◽  
Sintering Process ◽  
Nano Alumina

Si3N4/BN Composite Ceramics with Nd2O3-Al2O3-Y2O3 Ternary Additives by Pressureless Sintering

2010 ◽  
Vol 434-435 ◽  
pp. 106-108
Author(s):  
Ping Liu ◽  
Yong Feng Li ◽  
Xiang Dong Wang ◽  
Hai Yun Jin ◽  
Guan Jun Qiao
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Phase Transformation ◽  
Flexural Strength ◽  
Pressureless Sintering ◽  
Sintering Process ◽  
Composite Ceramics ◽  
Fracture Toughness Testing ◽  
Β Phase ◽  
Toughness Testing

Si3N4/BN composite ceramics with 25vol% h-BN were prepared by pressure-less sintering process with Nd2O3/Al2O3/Y2O3 as sintering additives. The effects of these ternary additives on the densification behaviors and mechanical properties were investigated. XRD and FESEM were used to investigate the α-β phase transformation and microstructure. The XRD results showed that α-Si3N4 has transformed to β-Si3N4 completely in all the samples during the pressureless sintering process. The line shrinkage increased with the Nd2O3 contents increasing, and the highest line shrinkage (7.75%) was observed when 4wt% Nd2O3 was added, then decreased. The same trends were observed in flexural strength and fracture toughness testing. The ternary additives of Y2O3-Al2O3-Nd2O3 could improve the density, strength and fracture toughness of the material effectively.

Preparation and Characterization of SiC/MoSi2 Composites from Powder Resulting from a Mechanical-Assistant Combustion Synthesis Method

2010 ◽  
Vol 105-106 ◽  
pp. 70-74
Author(s):  
Jian Guang Xu ◽  
Hui Qiang Li ◽  
Hou An Zhang
Keyword(s):  
Mechanical Properties ◽  
Cyclic Oxidation ◽  
Room Temperature ◽  
Synthesis Method ◽  
Pressureless Sintering ◽  
Sintering Process ◽  
Oxidation Properties ◽  
Mosi2 Composite

SiC reinforced MoSi2 composites have been successfully prepared by pressureless sintering from mechanical-assistant combustion synthesized powders. The sintering temperatures and holding time were 1500°C~1650°C at a heating rate of 10K/min and 1 hour, respectively. The microstructure and mechanical properties of the as-sintered composites were investigated. SEM micrographs of SiC/MoSi2 composites showed that SiC particles were homogeneously distributed in MoSi2 matrix. The Vickers hardness, flexural strength and fracture toughness of the SiC/MoSi2 composites were up to 15.50GPa, 468.7MPa and 9.35MPa•m1/2, respectively. The morphologies of fractured surface of the composites revealed the mechanism to improve mechanical properties of MoSi2 matrix. At last, the cyclic oxidation behavior of the composites was discussed. The results of this work showed that in situ SiC/MoSi2 composite powder prepared by MASHS technique could be successfully sintered via pressureless sintering process and significant improvement of room temperature mechanical and anti-oxidation properties could be achieved.

scholarly journals The impact of process parameters on mechanical properties of parts fabricated in PLA with an open-source 3-D printer

2015 ◽  
Vol 21 (5) ◽  
pp. 604-617 ◽  
Author(s):  
Antonio Lanzotti ◽  
Marzio Grasso ◽  
Gabriele Staiano ◽  
Massimo Martorelli
Keyword(s):  
Mechanical Properties ◽  
Open Source ◽  
Process Parameters ◽  
Computer Aided Design ◽  
Fused Deposition Modeling ◽  
Testing Machine ◽  
Main Process ◽  
Content Type ◽  
Fused Deposition ◽  
The Impact

Purpose – This study aims to quantify the ultimate tensile strength and the nominal strain at break (ɛf) of printed parts made from polylactic acid (PLA) with a Replicating Rapid prototyper (Rep-Rap) 3D printer, by varying three important process parameters: layer thickness, infill orientation and the number of shell perimeters. Little information is currently available about mechanical properties of parts printed using open-source, low-cost 3D printers. Design/methodology/approach – A computer-aided design model of a tensile test specimen was created, conforming to the ASTM:D638. Experiments were designed, based on a central composite design. A set of 60 specimens, obtained from combinations of selected parameters, was printed on a Rep-Rap Prusa I3 in PLA. Testing was performed using a JJ Instruments – T5002-type tensile testing machine and the load was measured using a load cell of 1,100 N. Findings – This study investigated the main impact of each process parameter on mechanical properties and the effects of interactions. The use of a response surface methodology allowed the proposition of an empirical model which connects process parameters and mechanical properties. Even though results showed a high variability, additional ideas on how to understand the impact of process parameters are suggested in this paper. Originality/value – On the basis of experimental results, it is possible to obtain practical suggestions to set common process parameters in relation to mechanical properties. Experiments discussed in the present paper provide a variety of data and insight regarding the relationship among the main process parameters and the stiffness and strength of fused deposition modeling-printed parts made from PLA. In particular, this paper underlines the shortage in existing literature concerning the impact of process parameters on the elastic modulus and the strain to failure for the PLA. The experimental data produced show a good degree of compliance with analytical formulations and other data found in literature.

Parametric study on tensile and flexural properties of ULTEM 1010 specimens fabricated via FDM

2021 ◽  
Vol 27 (2) ◽  
pp. 429-451
Author(s):  
Chrysoula Pandelidi ◽  
Tobias Maconachie ◽  
Stuart Bateman ◽  
Ingomar Kelbassa ◽  
Sebastian Piegert ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Process Parameters ◽  
Computer Aided Design ◽  
High Performance ◽  
Mechanical Performance ◽  
Fused Deposition Modelling ◽  
Controlled Cooling ◽  
Content Type ◽  
Fused Deposition

Purpose Fused deposition modelling (FDM) is increasingly being explored as a commercial fabrication method due to its ability to produce net or near-net shape parts directly from a computer-aided design model. Other benefits of technology compared to conventional manufacturing include lower cost for short runs, reduced product lead times and rapid product design. High-performance polymers such as polyetherimide, have the potential for FDM fabrication and their high-temperature capabilities provide the potential of expanding the applications of FDM parts in automotive and aerospace industries. However, their relatively high glass transition temperature (215 °C) causes challenges during manufacturing due to the requirement of high-temperature build chambers and controlled cooling rates. The purpose of this study is to investigate the mechanical properties of ULTEM 1010, an unfilled polyetherimide grade. Design/methodology/approach In this research, mechanical properties were evaluated through tensile and flexural tests. Analysis of variance was used to determine the significance of process parameters to the mechanical properties of the specimens, their main effects and interactions. The fractured surfaces were analysed by scanning electron microscopy and optical microscopy and porosity was assessed by X-ray microcomputed tomography. Findings A range of mean tensile and flexural strengths, 60–94 MPa and 62–151 MPa, respectively, were obtained highlighting the dependence of performance on process parameters and their interactions. The specimens were found to fracture in a brittle manner. The porosity of tensile samples was measured between 0.18% and 1.09% and that of flexural samples between 0.14% and 1.24% depending on the process parameters. The percentage porosity was found to not directly correlate with mechanical performance, rather the location of those pores in the sample. Originality/value This analysis quantifies the significance of the effect of each of the examined process parameters has on the mechanical performance of FDM-fabricated specimens. Further, it provides a better understanding of the effect process parameters and their interactions have on the mechanical properties and porosity of FDM-fabricated polyetherimide specimens. Additionally, the fracture surface of the tested specimens is qualitatively assessed.

Optimization of SLM productivity by aligning 17-4PH material properties on part requirements

2014 ◽  
Vol 20 (6) ◽  
pp. 444-448 ◽  
Author(s):  
A. B. Spierings ◽  
M. Schoepf ◽  
R. Kiesel ◽  
K. Wegener
Keyword(s):  
Mechanical Properties ◽  
Material Properties ◽  
Processing Parameters ◽  
Powder Layer ◽  
Clear Correlation ◽  
Porosity Level ◽  
Content Type ◽  
Wide Range ◽  
Material Porosity ◽  
Process Productivity

Purpose – The purpose of this study is the development of a global SLM-manufacturing optimization strategy taking into account material porosity and SLM process productivity. Selective laser melting (SLM) is a master forming process generating not only a near net shape geometry, but also the material with its properties. Research focuses primarily on optimal processing parameters for maximised material properties. However, the process allows also designing the material structure by internal porosity, affecting global material properties and the process productivity. Design/methodology/approach – The study investigates the influence of the main SLM process parameters on material porosity and consequently on the static mechanical properties of hardened SS17-4PH material. Furthermore, a model for the SLM scanning productivity is developed based on the SLM processing parameters. Findings – The results show a clear correlation between porosity level and mechanical properties. Thereby, the mechanical strength and material modulus can be varied in a wide range. The degree of internal material porosity can be correlated to the energy input defined by a set of SLM processing parameters, such as Laser power, powder layer thickness and scan speed, allowing pre-definition of a specific degree of porosity. Originality/value – Aligning of the SLM processing parameters to the technical material requirements of the parts to be produced, e.g. maximal stresses in service, required E-modulus or lightweight aspects, enlarges the general design space significantly. In combination with the presented model for the scanning productivity, it is further possible to optimize the SLM build rate.

The Preparation and Properties of Alumina Ceramics through a Two-Step Pressureless Sintering Process

2018 ◽  
Vol 922 ◽  
pp. 47-54
Author(s):  
Chang Suo Yuan ◽  
Zi Jing Wang ◽  
Qiang Zhi ◽  
Ya Ming Zhang ◽  
Xu Dong Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Relative Density ◽  
High Purity ◽  
Dominant Factor ◽  
Second Phase ◽  
Pressureless Sintering ◽  
Sintering Process ◽  
Alumina Ceramics ◽  
Soaking Time

In this paper, a high-dense alumina ceramics were prepared through the two-step pressureless sintering process with high-purity alumina powder as raw materials and high-purity MgO as sintering aids. The effects of the sintering temperature in the first-step (T1) and the soaking time (t) in the second sintering step (T2) on the density, microstructure and mechanical properties of the alumina ceramics were studied. The results indicated that the relative density increased with the increase of T1 temperature whereas it increased and then decreased with the increase of MgO content. Higher T1 temperature and extended soaking time caused larger grain size, which accompanied with the Ostwald ripening of the grain and led to non-uniformity of grain size distribution. The addition of MgO was beneficial to the decrease in grain size due to pinning effect of the second phase. For samples with shorter soaking time, sintering with higher T1 temperature led to better mechanical properties because of its high density. However, for the long soaking time, all samples after sintering at different T1 temperature were fully-densified, so the grain size become to the dominant factor of strength, thus samples with lower T1 temperature exhibited better mechanical properties due to the refinement grain. Excessive addition of MgO resulted in defects, by which the strength increased firstly and then decreased slightly with the increased MgO content. For the samples with 2.5wt.% MgO, the optimum condition for the two-step pressureless sintering was T1=1450°C and T2=1400°C for 20h, and the obtained sample achieved the relative density of 96% and the strength of 507±32MPa.

Manufacturing complex Al2O3 ceramic structures using consumer-grade fused deposition modelling printers

2020 ◽  
Vol 26 (6) ◽  
pp. 1035-1048 ◽  
Author(s):  
Nicholas A. Conzelmann ◽  
Lovro Gorjan ◽  
Fateme Sarraf ◽  
Lily D. Poulikakos ◽  
Manfred N. Partl ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Ceramic Powder ◽  
Compressive Force ◽  
Ethylene Vinyl Acetate ◽  
Ceramic Particle ◽  
Fused Deposition Modelling ◽  
Content Type ◽  
Fused Deposition ◽  
Debinding Process ◽  
Printing Direction

Purpose This study aims to fabricate complex ceramic tetrahedron structures, which are challenging to produce by more conventional methods such as injection molding. To achieve this aim, thermoplastic-ceramic composite filaments were developed and printed with unmodified, consumer-grade, fused deposition modelling (FDM) printers instead. Design/methodology/approach Al2O3 ceramic powder was mixed with ethylene vinyl acetate polymer as a binder (50 Vol.- per cent) to form a filament with a constant diameter of 1.75 mm. After the printing and thermal treatment stages, the shrinkage and mechanical properties of cuboid and tetrahedron structures were investigated. Findings The shrinkage of the parts was found to be anisotropic, depending on the orientation of the printing pattern, with an increase of 2.4 per cent in the (vertical) printing direction compared to the (horizontal) printing layer direction. The alignment of the ceramic particle orientations introduced by FDM printing was identified as a potential cause of the anisotropy. This study further demonstrates that using a powder bed during the thermal debinding process yields sintered structures that can withstand twice the compressive force. Originality/value Ceramic FDM had previously been used primarily for simple scaffold structures. In this study, the applicability of ceramic FDM was extended from simple scaffolds to more complex geometries such as hollow tetrahedra. The structures produced in this study contain dense parts printed from multiple contiguous layers, as compared to the open structures usually found in scaffolds. The mechanical properties of the complex ceramic parts made by using this FDM technique were also subjected to investigation.

scholarly journals Optimization of SLM process parameters for Ti6Al4V medical implants

2019 ◽  
Vol 25 (3) ◽  
pp. 433-447 ◽  
Author(s):  
Mahmoud Elsayed ◽  
Mootaz Ghazy ◽  
Yehia Youssef ◽  
Khamis Essa
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Process Parameters ◽  
Laser Power ◽  
Medical Implants ◽  
Power Laser ◽  
Porosity Level ◽  
Content Type ◽  
Scan Speed ◽  
Hatch Spacing

PurposeTi6Al4V alloy has received a great deal of attention in medical applications due to its biomechanical compatibility. However, the human bone stiffness is between 10 and 30 GPa while solid Ti6Al4V is several times stiffer, which would cause stress shielding with the surrounding bone, which can lead to implant and/or the surrounding bone’s failure.Design/methodology/approachIn this work, the effect of selective laser melting (SLM) process parameters on the characteristics of Ti6Al4V samples, such as porosity level, surface roughness, elastic modulus and compressive strength (UCS), has been investigated using response surface method. The examined ranges of process parameters were 35-50 W for laser power, 100-400 mm/s for scan speed and 35-120 µm for hatch spacing. The process parameters have been optimized to obtain structures with properties very close to that in human bones.FindingsThe results showed that the porosity percentage of a SLM component could be increased by reducing the laser power and/or increasing the scan speed and hatch spacing. It was also shown that there was a reverse relationship between the porosity level and both the modulus of elasticity and UCS of the SLM part. In addition, the increased laser power was resulted into a substantial decrease of the surface roughness of SLM parts. Results from the optimization study revealed that the interaction between laser process parameters (i.e. laser power, laser speed, and the laser spacing) have the most significant influence on the mechanical properties of fabricated samples. The optimized values for the manufacturing of medical implants were 49 W, 400 mm/s and 99 µm for the laser power, laser speed and laser spacing, respectively. The corresponding porosity, surface roughness, modulus of elasticity and UCS were 23.62 per cent, 8.68 µm, 30 GPa and 522 MPa, respectively.Originality/valuePrevious investigations related to additive manufacturing of Ti alloys have focused on producing fully dense and high-integrity structures. There is a clear gap in literature regarding the simultaneous enhancement and adjustment of pore fraction, surface and mechanical properties of Ti6Al4V SLM components toward biomedical implants. This was the objective of the current study.

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