The objective of this research is to perform the processing and mechanical characterization on 3D-printed high-temperature polymer (polycarbonate) reinforced with short carbon fiber (SCF) composite material fabricated with the help of fused filament fabrication process. For this study, different SCF volume fractions (3%, 5%, 7.5%, 10%) with varying printing speed (25, 50, 75 mm/s) are taken as the input variables. It was observed that tensile, flexural, compressive properties and micro-hardness were greatly affected by varying the input processing parameters. To find the orthotropic properties of 3D-printed specimens, tensile properties are analyzed on 0° in the X-Y plane, 90° in the X-Y plane, and 90° in Z-axis. Scanning electron microscopy (SEM) is performed to study the effect of fiber breakage, fiber distribution, fiber accumulation, and fiber length on the mechanical performance of the final part. After performing mechanical testing, investigation of microstructural behavior of tensile, flexural, and compressive samples is accomplished using SEM. From the micrograph analysis and mechanical testing, it was noticed that fiber behavior inside the composite has created a great influence in deciding the mechanical performance of the final part. Micromechanics and classical lamination theory phenomena are followed to determine the effective young’s modulus of 3D-printed samples mathematically. Printing direction and reinforcement percentage are found out to be the most influential parameters in deciding the final properties of 3D-printed specimens by using the statistical tool ANOVA. Response surface methodology is used to determine the optimum parameters to get good-quality print with SCF-reinforced PC.

Processing, mechanical characterization, and micrography of 3D-printed short carbon fiber reinforced polycarbonate polymer matrix composite material

In this study, the influence of multiwall carbon nanotubes (MWCNT) additions on the mechanical properties of sintered Ti6Al4V-based nanocomposites was investigated. The nanocomposites were fabricated with varying weight fractions of MWCNT (0.5, 1.0 & 1.5 wt%) using the spark plasma sintering (SPS) technique. Investigations were carried out using nanoindentation of varying indentation loads (50 mN, 75 mN and 100 mN) to assess the nanohardness (H) and reduced elastic modulus (Er) of the alloy and nanocomposites. Further analysis was done to evaluate the elastic recovery index ( W e W t ) , plasticity index ( W p W t ) , elastic strain resistance ( H E r ) and yield pressure ( H 3 E r 2 ) at the maximum load. Microstructural analysis revealed the presence of the MWCNT dispersed across the alpha and beta phases of the Ti6Al4V matrix. The nanoindentation studies showed that the nanohardness, elastic modulus, elastic recovery index, elastic strain resistance and anti-wear properties improved with the MWCNT addition and continually increased with increase in nanotubes content. Also, it was observed that the nanohardness and reduced elastic modulus of the fabricated nanocomposites are in the range of 4677–9276 MPa and 29.3–60.9 GPa respectively which declined with increase in indentation load. The sintered Ti6Al4V displayed the least resistance to plastic deformation.

Nanoindentation studies of the mechanical behaviours of spark plasma sintered multiwall carbon nanotubes reinforced Ti6Al4V nanocomposites

DMLS or Direct Metal Laser Sintering is a technique which can be classified under an additive manufacturing (AM). In this technique, metal powders are used to manufacture the parts or components in a layer by layer fashion. This technique is widely adopted by manufacturing industries, aerospace, automobile, naval, biomedical and other industries. Recent developments of high power laser and fiber optics have also enabled DMLS to process the metallic powders in an efficient manner. So far, the DMLS process has encountered several issues or challenges during the operation. This review presents the DMLS operation and the several issues arising during this process. These issues or challenges are metallurgical defects (balling, porosity and delamination), microstructural change and evaluation of mechanical properties such as high residual stress, tension and compression behavior, surface roughness and wear analysis. In this paper, an attempt has been made to address all the issues or challenges arising during the DMLS process. This paper also deals with the significant effect of process parameters on the allied properties of DMLS processed parts. High temperature (or high thermal gradients) along with high cooling rate and further heat treatment associated with the process have a significant impact on the change in microstructural behavior and residual stresses. Thus, different control methods are discussed to tackle all the issues or challenges arising during the process i.e. to alleviate the process defects, regulate the cooling rate and heat treatment to tackle the microstructure, mechanical properties, residual stresses, and corrosion behavior.

Issues in fabrication of 3D components through DMLS Technique: A review

3D printing or additive manufacturing is an emerging technique for the fabrications of biomedical components. Several researchers are working on fabrications of the biomedical components, future prospective of implantation, and transplantation aspects. The current review presents a meticulous summary of research work done so far by the researchers in the view of design and fabrications about biomedical components by using 3D printing technology such as fused deposition modeling (FDM), inkjet printing, stereolithography, and selective laser sintering (SLS). The design and fabrications of biomedical components include 3D printing of bone, low-cost high-quality prosthetics, intervertebral disks, medical equipment, heart valve, building tissues using blood vessels and drugs. The objective of this review article is to explore different additive manufacturing processes, challenges, and future developments for 3D printing for biomedical components.

https://link.springer.com/content/pdf/10.1007/s11665-021-05792-3.pdf

3D Printing Technology for Biomedical Practice: A Review

Metal additive manufacturing (AM) has gained much attention in recent years due to its advantages including geometric freedom and design complexity, appropriate for a wide range of potential industrial applications. However, conventional metal AM methods have high-cost barriers due to the initial cost of the capital equipment, support, and maintenance, etc. This study presents a low-cost metal material extrusion technology as a prospective alternative to the production of metallic parts in additive manufacturing. The filaments used consist of copper, bronze, stainless steel, high carbon iron, and aluminum powders in a polylactic acid matrix. Using the proposed fabrication technology, test specimens were built by extruding metal/polymer composite filaments, which were then sintered in an open-air furnace to produce solid metallic parts. In this research, the mechanical and thermal properties of the built parts are examined using tensile tests, thermogravimetric, thermomechanical and microstructural analysis.

Mechanical and Thermal Analyses of Metal-PLA Components Fabricated by Metal Material Extrusion

The present work deals with the fabrication of silicon carbide (SiC) reinforced Ti6Al4V metal matrix composites (MMC’s) by a direct metal laser sintering process, followed by characterization of microstructures and evaluation of mechanical properties. Variable process parameters like laser power density [3.528–5.172 W/cm2 (×104)], SiC reinforcements (5%–15% by volume), and beam scanning speed (3500–4500 mm/min) and constant process parameters such as spot diameter (0.4 mm), hatching gap (0.2 mm), and layer thickness (0.4 mm) were considered to perform the experiments. The influence of addition of reinforcements on mechanical and physical properties of fabricated samples as compared to Ti6Al4V was examined. Field emission scanning electron microscope images show good metallurgical bonding between reinforcement and matrix. The presence of intermetallic compounds formed during the sintering process was detected by x-ray diffraction, which enhances the mechanical properties of the fabricated samples. Density of sintered samples increased on the increment in laser power density but decreased with an increase in the percentage of SiC in the mixture. Mean value of coefficient of friction was found in the range of 0.157–0.115 in a testing duration of 10 min, showing improvement in the wear resistance property as compared to Ti6Al4V. The improved mechanical properties and surface characteristics result in the formation of effective MMC's for various engineering applications.

Saurav Misra

Papers

Fabrication and characteristic evaluation of direct metal laser sintered SiC particulate reinforced Ti6Al4V metal matrix composites