Fabrication of Meso- and Micro-Structured Devices by Direct-Write Deposition and Laser Processing of Dry Fine Powders

2004 ◽  
Author(s):  
Pranav Kumar ◽  
Suman Das
Keyword(s):  
High Frequency ◽  
Heterogeneous Material ◽  
Functionally Graded ◽  
Powder Materials ◽  
Direct Write ◽  
Feature Size ◽  
Fine Powders ◽  
Powder Particles ◽  
Multiple Materials ◽  
Spatially Varying

We present a multi-material rapid prototyping technique for producing 2D and layered 3D meso- and micro-structured multi-functional devices with spatially varying heterogeneous material compositions. This technique involves direct-write deposition of multiple, patterned powder materials followed by laser sintering. The direct-write deposition system features miniature hopper-nozzles for depositing dry powdered materials by gravity or by high frequency vibration-assisted flow on to a movable substrate. Deposition of 10–125μm powder particles via 100μm-2mm hopper-nozzles orifices has yielded a 100μm minimum attainable feature size for device footprints ranging from sub-milimeter to a few centimeters. The feasibility of this direct-write concept was proved by patterning single and multiple materials onto substrates to demonstrate various prototype devices envisaged by this technique. These include micro-battery, interdigitated capacitor, fractal antenna, Swiss-roll microcombustor, and functionally graded polymeric bioimplants.

Direct-Write Deposition and Laser Processing of Dry Fine powders

2004 ◽  
Vol 860 ◽  
Author(s):  
Pranav Kumar ◽  
Suman Das
Keyword(s):  
Powder Material ◽  
High Frequency ◽  
Laser Processing ◽  
Solid Freeform Fabrication ◽  
Powder Materials ◽  
Direct Write ◽  
Direct Writing ◽  
Dual Wavelength Laser ◽  
Freeform Fabrication ◽  
Fine Powders

ABSTRACTWe present a concept for multi-material solid freeform fabrication of 2D and layered 3D heterogeneous components. This technique involves direct-write deposition of multiple, patterned powder materials followed by laser processing. The direct-write deposition system features miniature hopper-nozzles for depositing dry powdered materials by gravity or by high frequency vibration-assisted flow onto a movable substrate. A dual wavelength laser processing workstation was used to consolidate the deposited pattern to desired densities. The feasibility of this concept was proved by direct-writing and laser processing various powder material patterns.

INCREASING THE WEAR RESISTANCE OF THE WORKING BODIES OF AGRICULTURAL MACHINES BY THE HDTV METHOD WITH ADDING POWDER OF THE EED METHOD

2020 ◽  
Vol 4 (141) ◽  
pp. 123-131
Author(s):  
IL’YA ROMANOV ◽  
Keyword(s):  
Wear Resistance ◽  
Abrasive Wear ◽  
High Frequency ◽  
Machine Building ◽  
Abrasive Wear Resistance ◽  
Research Purpose ◽  
Powder Materials ◽  
Agricultural Machinery ◽  
Resource Saving ◽  
Working Bodies

The development of energy and resource-saving methods and technologies for strengthening and restoring the working bodies of agricultural machinery will increase their abrasive wear resistance and durability by using materials from machine-building waste and reduce the cost by 10-30 percent without reducing operational characteristics. (Research purpose) The research purpose is in increasing the abrasive wear resistance and durability of cultivator legs by surfacing powder materials obtained by electroerosive dispersion from solid alloy waste by high-frequency currents. (Materials and methods) Authors obtained a powder for research on their own experimental installations of the CCP "Nano-Center" of electroerosive dispersion from waste of sintered hard alloys of the T15K6 brand. The microhardness of powders and coatings on microshifts was measured using the PMT-3 device, and the hardness of coatings with the KMT-1 microhardometer was measured using the Rockwell method according to GOST 9013-59. The microwave-40AV installation was used to assess the wear resistance of materials of working bodies of tillage machines. (Results and discussion) In the course of laboratory wear tests the relative wear resistance of samples hardened by high-frequency surfacing currents significantly exceeds the wear resistance of non-hardened samples made OF 65g steel, accepted as the reference standard. (Conclusions) Based on the results of experimental studies, the article proposes a new resource-saving technological process for strengthening the working bodies of agricultural machinery through the use of materials from machine-building waste, which allows increasing the abrasive wear resistance of working bodies by 1.5-2 times due to the use of tungsten-containing materials.

Effect of Composition on the Morphology and Hardness of Nanostructured Cu Based Composite and Alloy Powders/Granules Produced by High Energy Mechanical Milling

2007 ◽  
Vol 29-30 ◽  
pp. 143-146 ◽  
Author(s):  
Aamir Mukhtar ◽  
De Liang Zhang ◽  
C. Kong ◽  
P. R. Munroe
Keyword(s):  
Grain Size ◽  
Mechanical Milling ◽  
Alloy Powder ◽  
High Energy ◽  
Al2o3 Nanoparticles ◽  
X Ray ◽  
Fine Powders ◽  
Average Grain Size ◽  
Powder Particles

Cu-(2.5 or 5.0vol.%)Al2O3 nanocomposite balls and granules and Cu-(2.5vol.% or 5.0vol.%)Pb alloy powder were prepared by high energy mechanical milling (HEMM) of mixtures of Cu and either Al2O3 or Pb powders. It was observed that with the increase of the content of Al2O3 nanoparticles from 2.5vol.% to 5vol.% in the powder mixture, the product of HEMM changed from hollow balls into granules and the average grain size and microhardness changed from approximately 130nm and 185HV to 100nm and 224HV, respectively. On the other hand, HEMM of Cu–(2.5 or 5.0vol.%) Pb powder mixtures under the same milling conditions failed to consolidate the powder in-situ. Instead, it led to formation of nanostructured fine powders with an average grain size of less than 50nm. Energy dispersive X-ray mapping showed homogenous distribution of Pb in the powder particles in Cu–5vol.%Pb alloy powder produced after 12 hours of milling. With the increase of the Pb content from 2.5 to 5.0 vol.%, the average microhardness of the Cu-Pb alloy powder particles increases from 270 to 285 HV. The mechanisms of the effects are briefly discussed.

Approximate Functionally Graded Materials for Multi-Material Additive Manufacturing

2018 ◽  
Author(s):  
Yuen-Shan Leung ◽  
Huachao Mao ◽  
Yong Chen
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Functionally Graded Materials ◽  
Functionally Graded ◽  
Gradual Transition ◽  
Material Distribution ◽  
Graded Materials ◽  
Base Materials ◽  
Multiple Materials ◽  
Am Processes

Functionally graded materials (FGM) possess superior properties of multiple materials due to the continuous transitions of these materials. Recent progresses in multi-material additive manufacturing (AM) processes enable the creation of arbitrary material composition, which significantly enlarges the manufacturing capability of FGMs. At the same time, the fabrication capability also introduces new challenges for the design of FGMs. A critical issue is to create the continuous material distribution under the fabrication constraints of multi-material AM processes. Using voxels to approximate gradient material distribution could be one plausible way for additive manufacturing. However, current FGM design methods are non-additive-manufacturing-oriented and unpredictable. For instance, some designs require a vast number of materials to achieve continuous transitions; however, the material choices that are available in a multi-material AM machine are rather limited. Other designs control the volume fraction of two materials to achieve gradual transition; however, such transition cannot be functionally guaranteed. To address these issues, we present a design and fabrication framework for FGMs that can efficiently and effectively generate printable and predictable FGM structures. We adopt a data-driven approach to approximate the behavior of FGM using two base materials. A digital material library is constructed with different combinations of the base materials, and their mechanical properties are extracted by Finite Element Analysis (FEA). The mechanical properties are then used for the conversion process between the FGM and the dual material structure such that similar behavior is guaranteed. An error diffusion algorithm is further developed to minimize the approximation error. Simulation results on four test cases show that our approach is robust and accurate, and the framework can successfully design and fabricate such FGM structures.

scholarly journals Influence of parameters of impulse laser impact on the formation of the gradient of the structure of porous titanium powder

2018 ◽  
pp. 88-94
Author(s):  
D. V. Minko
Keyword(s):  
Laser Radiation ◽  
Titanium Powder ◽  
Structural Characteristics ◽  
Selective Laser Sintering ◽  
Light Flux ◽  
Laser Action ◽  
Pulsed Laser ◽  
Powder Materials ◽  
Solid Core ◽  
Powder Particles

The possibility of selective laser sintering of graded porous and compactly porous structures by surface fusion of powder particles is demonstrated while maintaining a solid core, which leads to the formation of interparticle contacts in the presence of a liquid phase. The interaction of the light flux of the laser pulse with the surface of the powder particles under multiple reflection is considered. It is shown that the effect of single pulses of laser radiation leads to the formation of sintered structural elements of a powder material having a diameter approximately equal to the diameter of the focal spot. Technological regimes of pulsed laser action are established at which steady contact formation of titanium powder particles of the fractional compositions under study occurs. The possibility of obtaining powder materials with a gradient structure by controlling the parameters of pulsed laser action is experimentally demonstrated. It was found that accurate dosing of thermal energy and the number of pulses of laser radiation makes it possible to minimize shrinkage of powder layers in the absence of particle conglomeration, to control the structural characteristics and properties of products, to preserve the microstructure and phase composition of the initial materials.

scholarly journals Computer modelling and simulation of a novel printing head for complex tissue engineering constructs

2020 ◽  
Vol 318 ◽  
pp. 01045
Author(s):  
Gokhan Ates
Keyword(s):  
Tissue Engineering ◽  
Computer Modelling ◽  
Three Dimensional ◽  
Biological Tissues ◽  
Biological Properties ◽  
Functionally Graded ◽  
Mixing Efficiency ◽  
Tissue Constructs ◽  
Multiple Materials ◽  
Graded Structures

In tissue engineering, three-dimensional functional scaffolds with tailored biological properties are needed to be able to mimic the hierarchical structure of biological tissues. Recent developments in additive biomanufacturing allow to extrude multiple materials enabling the fabrication of more sophisticated tissue constructs. These multi-material biomanufacturing systems comprise multiple printing heads through which individual materials are sequentially printed. Nevertheless, as more printing heads are added the fabrication process significantly decreases, since it requires mechanical switching among the physically separated printheads to enable printing multiple materials. In addition, this approach is not able to create biomimetic tissue constructs with property gradients. To address these limitations, this paper presents a novel static mixing extrusion printing head to enable the fabrication of multi-material, functionally graded structures using a single nozzle. Computational fluid dynamics (CFD) was used to numerically analyze the influence of Reynolds number on the flow pattern of biomaterials and mixing efficiency considering different miscible materials.

Aerosol Printing of High Resolution Films for LTCC-Multilayer Components

2012 ◽  
Vol 9 (3) ◽  
pp. 133-137 ◽  
Author(s):  
Martin Ihle ◽  
Uwe Partsch ◽  
Sindy Mosch ◽  
Adrian Goldberg
Keyword(s):  
High Resolution ◽  
High Frequency ◽  
High Reliability ◽  
Direct Write ◽  
Printing Technology ◽  
Fine Line ◽  
Aerosol Printing ◽  
Fine Structures ◽  
Cost Efficient ◽  
Printing Parameters

For the electronic packaging of sensor stable and cost-efficient fine line printing technologies on LTCC and high frequency laminates are needed. Especially common technologies like screen printing and thin film techniques are unsuitable for fine structures or too expensive. In addition, there is no direct write technology for 3D LTCC designs as well as for high reliability cofiring structures. Closing this gap, aerosol printing technology is used to print high resolution conductors on planar and nonplanar substrates. Aerosol printing is a direct write noncontact printing technology of functional layers. After pneumatic atomization, the ink is transformed into 1–5 μm droplets. The resulting continuous aerosol stream is focused by a sheath gas in the printing head. Thus, the long standoff distance between the substrate and the deposition tip of max. 5 mm allows 3D printing on nonplanar substrates. With optimized inks and printing parameters, line widths of 10 μm are achievable. This paper will present applications for aerosol printed functional layers on LTCC. These are, for example, aerosol printed films embedded in cofired LTCC, fine line structures for high frequency applications, and the evaluation of printed 3D structures like LTCC stairways. Furthermore, the 90° contact of unconventional sensor designs will be presented.

Laminated and Functionally Graded Ceramics by Electrophoretic Deposition

2007 ◽  
Vol 333 ◽  
pp. 49-58 ◽  
Author(s):  
Omer Van der Biest ◽  
L. Vandeperre ◽  
Stijn Put ◽  
Guy Anné ◽  
Jef Vleugels
Keyword(s):  
Silicon Carbide ◽  
Electrophoretic Deposition ◽  
High Hardness ◽  
Functionally Graded ◽  
Advanced Ceramics ◽  
Graded Materials ◽  
High Toughness ◽  
Mode Of Failure ◽  
Powder Particles ◽  
Powder Suspension

Electrophoresis is the effect that when an electric field is applied to a suspension of a powder in a liquid, the powder particles move under influence of this field. Frequently the powder particles also deposit at one of the electrodes. The form of the electrode determines the form of the deposit, hence shaping is possible. The current insights into the science and technology of electrophoretic deposition (EPD) will be summarized. EPD is well suited for shaping layered microstructures (laminates), by simply changing repeatedly between two or more suspensions during deposition. Tubular laminates consisting of silicon carbide layers and crack deflecting graphite interlayers have been produced. These tubes demonstrate an enhanced fracture energy and a gradual mode of failure. Another area of advanced ceramics where the use of EPD makes sense are functionally graded materials (FGM) in which one tries to combine in one component high hardness and high toughness. EPD allows the formation of FGM by depositing from a powder suspension to which a second suspension is continuously added during the process. An example will be shown of a graded WC-Co hardmetal.

scholarly journals STUDY PARTICLE SIZE DISTRIBUTION OF ERODING POWDER LEAD BRONZES OBTAINED IN DISTILLED WATER

2018 ◽  
Vol 22 (4) ◽  
pp. 42-49
Author(s):  
E. V. Ageev ◽  
A. S. Pereverzev ◽  
A. S. Osminina ◽  
I. Yu. Grigorov
Keyword(s):  
Particle Size ◽  
Average Particle Size ◽  
Discharge Zone ◽  
Powder Materials ◽  
Average Particle ◽  
Distilled Water ◽  
Powder Particles ◽  
Local Exposure ◽  
Finely Dispersed Powder ◽  
Powder Lead

The article is devoted to the current problem of processing waste of conductive materials, in particular lead bronze, which accumulates in large quantities at enterprises. A promising method for processing any conductive material, characterized by wastelessness, ecological purity of the process, and low energy costs, is the method of electroerosive dispersion. The essence of the method of electroerosive dispersion is the destruction of current-conducting material as a result of local exposure to short-term electrical discharges between the electrodes. In the discharge zone, under high temperatures, heating, melting and partial evaporation of the material occurs, resulting in the formation of finely dispersed powder particles. At the same time, the electrical parameters of the installation will affect the productivity of the process for obtaining powder materials: the voltage at the electrodes, the capacitance of the discharge capacitors, and the repetition rate. The article presents the results of the analysis of particles of powdered lead bronze obtained by the method of electroerosive dispersion in distilled water from wastes, using the laser analyzer of particle sizes "Analysette 22 NanoTec". It has been experimentally established that the average particle size of powdered lead bronze is 9.73 μm, the arithmetic value is 9.731 μm. It was also found that the elongation coefficient (elongation) of particles with a size of 7.188 μm is 1.50.

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