Bronze Particles Research Articles

3d printing of a continuous carbon fiber reinforced bronze-matrix composite using material extrusion

The main objective of this study is to investigate, for the first time, the feasibility of 3d printing a continuous carbon fiber (CCF) reinforced metal matrix composite using a cost-effective material extrusion (MEX) technology. Notably, this paper presents a detailed analysis of the microstructure and mechanical and physical properties of a bronze matrix composite reinforced with CCF. The results reveal that CCF significantly impedes the expected densification levels of the composite's structure, causing extensive gaps between the bronze particles. However, despite the high porosity level, the composite's electrical conductivity remains relatively high, demonstrating the limited negative impact of the CCF material on the composite's conductivity. Moreover, mechanical evaluations were performed through 3-point bending and tensile tests, highlighting the composite material's advantages and limitations. The results show that the composite material exhibits an improved yield stress of 76 %, increased ultimate tensile strength of 20 %, and an extended fracture strain of 30 %. However, the flexural strength decreases by 23 % due to the presence of massive gaps formed by CCF.

Numerical investigations of heat transfer and pressure drop in packed bed duct exposed to forced convection boundaries under local thermal non-equilibrium conditions

The present study is a 2-D numerical study which discusses the thermohydraulic performance of packed bed duct under local thermal non-equilibrium and steady state conditions exposed to forced convection boundaries (BC-6). The numerical model is well validated with the experimental work reported in the literature and found to be accurate enough to perform further parametric investigations. The analysis is done to see the effect of different ball diameter (5 mm, 9 mm and 11 mm), bed porosity, heat transfer fluid (air, water and engine oil - Pr = 0.70–645) and ball material (EPS, steel and bronze) on heat transfer and fluid flow characteristics in turbulent flow region of Reynolds number ranging from 900 to 14,320. The numerical results obtained using commercial CFD software COMSOL shows that, the heat transfer coefficient and pressure drop in packed bed increases with increase in ball diameter, thermal conductivity of ball and bed porosity which is exactly reverse as reported in literature for BC-1 to BC-5. The maximum thermal performance factor with bronze particles is 2.45 and 24.5 times more than stainless steel and EPS particles respectively for larger particle size and bed porosity. Engine oil exhibits significantly higher heat transfer coefficient (9.7 × 105 W/m2K) and pressure drop (3.3 × 106 Pa) compared to water (40,126 W/m2K and 2028 Pa) and air (600 W/m2K and 250 Pa) respectively. Overall, the combination of water as heat transfer fluid along with bronze particles of larger diameter and larger bed porosity emerges as the optimal choice for enhancing heat transfer in the packed duct exposed to forced convection boundary condition BC-6.

Investigation of Tribological Behavior of PTFE Composites Reinforced with Bronze Particles by Taguchi Method

Reinforced PTFE materials can be designed to show high mechanical stability against harder materials under sliding wear conditions. Especially bearing metal-reinforced PTFE is of high practical interest. In this class of materials, bronze-filled PTFE was reported to obtain high wear resistance, a low coefficient of friction (COF), and excellent self-lubrication properties in sliding conditions. In the statistical approach of this work, PTFE composites reinforced with 25 vol%, 40 vol%, and 60 vol% bronze particles were evaluated against pure PTFE regarding wear behavior under varied wear test parameters, i.e., material, normal load, and sliding speed. Wear tests were planned to use a standard orthogonal array based on the Taguchi design method. An analysis of variance test was utilized to quantify the effects of test parameters on the wear behavior of the bronze/PTFE composites and pure PTFE. According to the variance analysis, the material type has the largest influence on the COF and the specific wear rate (SWR) under test conditions of this work. Both COF and SWR were found to be influenced by the material type (29.83% and 96.16%), the normal load (33.34% and 0.95%), and sliding speed (9.14% and 1.28%). The lowest SWR and COF values were achieved at the optimum wear test conditions where the wear test parameters were 1 m/s sliding speed (A4B2C2) at PTFE + 60 vol.% bronze reinforced composite 50 N application load and 0.32 m/s sliding speed (A4B3C1) at PTFE + 60 vol.% bronze reinforced composite 100 N application load, respectively.

Synthesis and characterization of MWCNTs nanocomposite for fabrication of tensometric transducers

A nanocomposite was prepared using MWCNTs and micro-sized bronze particles dispersed in elastomer silicone organic compound (SILAGER 8030). The nano-composite was characterized by FT-IR, SEM, EDS and Raman spectroscopy; showing the rough surface of the composite with interweaving of nano threads. This nano-composite was used to manufacture strain gauge. The conductivities were measured concerning wt% of micro-sized bronze, compression and time. The maximum electrical conductivity obtained was 2.1 S/m at 5.0 wt% bronze metal alloy and MWCNT (3.0 wt%) at 16% compression. With increasing amplitude and frequency of ultrasonic exposure, an increase in the pressure associated with cavitation in the liquid was observed. Each value of ultrasound exposure corresponded to a certain value of electrical resistance. At the same time, with an increase in the intensity of the cavitation effect on the strain gauge transducer, extremum points appeared, which corresponded to a decrease in resistance. The developed material is highly useful for manufacturing strain gauges to be used in liquid ring vacuum pumps as a measuring transducer of liquid ring pressure into signals associated with changes in resistance. This allows liquid ring vacuum pumps to be precisely controlled; improving their energy efficiency and reliability.

Effect of filling materials on the tribological performance of polytetrafluoroethylene in different wear modes

AbstractAs it is known, Polytetrafluoroethylene (PTFE) is one of the most preferred polymeric materials for tribological applications. This study investigates the performance of PTFE and its composites under different tribological conditions. The effects of short glass fiber (GF), carbon particle (CP) and bronze particle (BP) reinforcement agents and their hybrid filling with molybdenum disulfide (MoS2) on sliding, erosive and abrasive wear were examined. Sliding tests were carried out with a ball‐on‐disc test apparatus, erosive wear tests were carried out with solid particle erosion and abrasive wear tests were carried out with a scratch test. It has been found that reinforcement agents improve sliding and abrasive wear resistance but worsen the erosion resistance. The hardness and contact angle of the samples were associated with their wear performances. Topographic and morphological analyzes of worn surfaces were performed using optical profilometer and scanning electron microscopy (SEM), respectively, and wear mechanisms were discussed.Highlights Filling materials (glass fiber, carbon particle and bronze particle) increase the adhesion and abrasion resistance of PTFE, while decreasing its erosion resistance. The effect of hybrid addition of MoS2 solid lubricant on wear performances depends on the type of filler. There is a correlation between surface properties (hardness and contact angle) and wear performances. Optical profilometer and scanning electron microscopy were used to examine wear mechanisms.

Tensile, flexural and fracture properties of MEX-printed PLA-based composites

Due to the continuous development of material extrusion-additive manufacturing (MEX-AM) technology, the fracture behavior of polymeric parts, and especially of their associated composites, presents some shortcomings and also a challenge in the field. In this paper, the fracture properties of non-reinforced (NR) and reinforced Polylactic Acid (PLA) samples manufactured by MEX-AM process are investigated through tensile, flexural and fracture mechanics tests. The samples are reinforced with glass fibers (GF-PLA), carbon fibers (CF-PLA) and bronze particles (BP-PLA), and tested parallel (named FLAT for all tests) and normal (named UPRIGHT for tensile test, and ON-EDGE for flexural and fracture mechanics tests) to the layer growth (LG). It was found that regardless of the type of test, the LG and the material significantly influence the mechanical properties and collapse modes of the MEX-printed samples. It was obtained that the parallel-LG load is favorable for the tensile and flexural tests, and the normal-LG for the fracture mechanics tests. Overall, the NR-PLA material gives the best strength, strain and energy absorption properties, CF-PLA stands out as the stiffest material, while BP-PLA presents the minimum performances for almost all properties. The macroscopic analyzes of the fractured samples clearly highlight distinct failure mechanisms associated with each type of test, material and LG. From the analysis of the mechanical behavior and macrostructural images, CF-PLA was identified as the most brittle material, and NR-PLA the most ductile.

Investigation of the Durability and Performance of Gears Made of Glass Fiber, Carbon and Bronze-Reinforced Polytetrafluoroethylene Matrix Composite Material

Polymer gears are often used in power transmission due to their numerous advantages. Heat accumulates on polymer gears during operation. Over time, this accumulated heat leads to damage; and shortens the service life of the gears. To prevent this, various fillers are added to the polymer materials. These fillers help to dissipate the heat generated on the gears. In this study, 25% glass fibers, 35% carbon powder, and 60% bronze particles were added to the polytetrafluoroethylene (PTFE) matrix to determine the wear behavior of gears. The properties of the matrix and the filler mainly influence the wear behavior of PTFE composites. The study showed that all composite gears with filler have better wear resistance than pure PTFE gears due to their better thermal stability. After the tests, it was found that the gears made of PTFE + 35% carbon additive had about 12 times better wear rates than those made of pure PTFE. Based on the average temperature values of the experiment, it was found that the mass temperature of gears made of 35% carbon-doped PTFE is about 38-39% lower than that of pure PTFE. This study contributes to the standard studies on heat build-up, thermal damage, and wear of gears made of polymers with different fillers and ratios.

Effect of Fillers on Mechanical Properties of FDM printed PLA Components

Fused Deposition Modelling (FDM) is the most accessible additive technology nowadays, because it combines the low cost and simplicity of the machine with the low cost and availability of the thermoplastic polymers. This class of polymers are however limited and in order to increase the application range of the products, mixing polymeric matrix with various fillers can be a solution.The purpose of this study is to identify the effect of the functional fillers incorporated in PLA thermoplastic on the mechanical properties of the obtained components. In addition, the layer orientation in relation to the loading direction will be considered as a study variable. All samples were manufactured under the same conditions using the same FDM machine. The effect of carbon / glass fibers and bronze particle fillers on the PLA matrix in comparison with the pure PLA filament was evidenced by tensile and flexural testes. The results were then interpreted based on the two criteria: filler type and layer deposition in accordance to the loading direction. It was determined that regardless of the type of test (tensile or flexural), the mechanical behavior is strongly influenced by the type of filler in the matrix. The most ductile behavior was showed by the pure PLA samples, and the most brittle by the PLA reinforced with carbon fibers.

Destruction mechanisms of epoxybased composite filled with metal powder under cavitation attack

The samples of epoxy compound with a powder filler and without it are tested on cavitation wear. The powder of aluminum bronze BrAZhNMts9–4–4–1 is used as a filler. The powder is obtained by filing the rod of the bronze. The composition of the epoxy compound is 100 parts of the resin K‑153 plus 12 parts of the hardener (polyethylene epolyamine). The distribution of the bronze particles in the epoxy compound follows the law close to the exponential one, the average particle size is equal to approximately 27 μm, and the volume fraction of the bronze powder in the compound is about 9,5 percent. The tests are conducted using the ultrasonic magnetostrictve vibrator UZDN‑2T in fresh water of room temperature, the frequency and amplitude of the vibrator horn end equal to 22 kHz and 28 µm respectively. The distance between the horn end and the sample surface is 0,5 mm. During the experiments the wear of the samples is evaluated by their weighting on analytical scales with step-type indication of 0,1 mg, measuring the surface roughness and the microhardness of the bronze particles in the composite is carried out as well. It has been shown that the addition of the bronze particles into the epoxy compound not only changes the kinetics of cavitation wear of the polymer but also decreases its cavitation resistance. The decrease in cavitation resistance caused by bronze particles addition is attributed to the fact, that the boundary between a metal particle and epoxy matrix is a «weak» spot, and the destruction of polymer begins from this boundary area under cavitation attack.

Microdrilling Studies PLA/Bronze Composite Samples Printed Using Fused Deposition Model

Fused deposition models (FDMs) are the latest trends for constructing complicated and instinctive 3D printing. Polylactic acid (PLA) is the most widely used raw material in extrusion-based three-dimensional (3D) printing in many areas since it is biodegradable and environmentally friendly; however, its utilization is limited due to some of its disadvantages such as mechanical weakness and water solubility rate. To increase the mechanical properties of the FDM, nano bronze particles have been added as advanced research. Printing the hole less than a millimetre is complicated, and there is a limited report available in FDM. In this paper, polylactic acid (PLA) with a 14% bronze composite filament is made by hot extruding under the desired FDM conditions. The samples are built with 100% infilled density with 45° orientation to a sample size of 50 × 50 × 10 mm. To examine the printing state and the effect of microdrilling on the printed specimen, two different specimens are printed with and without holes. An industrial drill with specified feed, speed, and cutting width is used to perform the test. The size of the drilled hole is checked by scanning electron microscopy. The quality of the drilled hole and the wear of the tool is investigated and reported. According to the observation, it is noted that the secondary machining operation becomes unavoidable to have a hole of less than a millimetre. Machining, cutting speed, and feed speed influence the delamination zone and the circumference of the hole.

Aerosol-assisted process to produce sodium tungsten bronze particles from aqueous solutions and effect of particle size on the NIR shielding performance

Aerosol-assisted process to produce sodium tungsten bronze particles from aqueous solutions and effect of particle size on the NIR shielding performance

Experimental study on aluminium bronze coatings fabricated by low pressure cold spraying and subsequent heat treatment

Among bronze alloys, strength and corrosion resistance are the distinguishing features of aluminium bronzes. CuAl alloys coatings are commonly prepared using thermal spraying technologies, but low-pressure cold spray, unpopular for this purpose so far, seems to be a good alternative in terms of manufacturing and facility costs. The research studies the effect of aluminium addition on low-pressure cold spray deposition of mixed CuAl feedstock powders (up to 30 wt% of Al) instead of bronze particles. Additionally, hard alumina particles (of the same weight as CuAl feedstock powders together) were added to lower coating porosity, provide good adhesion, and tailor the mechanical properties of coatings. After the implementation of thermal treatment, fine mixing of feedstock powders within the coating facilitated the formation of copper-rich solid solution and Cu4Al9 intermetallic phase for high amounts of Al (≥25 wt%). The coatings were characterized through light and scanning electron microscopy to examine cross-section morphology; energy-dispersive X-ray spectrometry and X-ray diffraction to investigate elemental and phase composition before and after thermal treatment. Additionally, to quantify the individual phases in sprayed coatings Rietveld refinement was performed. For coatings after thermal treatment were bronze formation was observed, the maximum solubility of aluminium in the copper structure was also determined using Vegard's linear dependence.

Influence of the content of dispersed fillers of various nature in polyvinylidene fluoride on its structural parameters and thermal conductivity

In this work, a comprehensive study of the effect of graphite and bronze particles on the structure and thermal conductivity of polyvinylidene fluoride (PVDF) was carried out. Based on the experiments carried out, it was found that at the limit of a relatively small concentration of bronze, the melting point of PVDF exceeds, and this was confirmed by an increase in the longitudinal dimensions of the crystallites. With relatively small amounts of fillers contained in the polymer composite materials (PCM, it was written that the change in thermal conductivity occurs mainly due to changes in the polymer structure. It was found out that the change in the structure of the polymer component in the compound and the thermal conductivity largely depends on the nature of the fillers.

Tribological behaviour of PTFE composites: Interplay between reinforcement type and counterface material

In this paper, we studied the sliding wear behaviour of polytetrafluoroethylene (PTFE)-based composites under conditions relevant to rotary seals. We specifically aimed to investigate the interactions between different particle-based reinforcements (lamellar or spheroidal bronze particles, PEEK particles) and different counterfaces (uncoated or Cr2O3-coated stainless steel), building upon our own previous work on fibre reinforced-composites to make up for the paucity of literature papers on the role of counterfaces. Pin-on-disc tests were performed under different load and speed conditions using spherical-tipped composite pins against coated or uncoated stainless steel discs to mimic the (initially) non-conformal, unidirectional sliding contact of lip seals. Though all composites attained a steady-state regime controlled by a tribochemical wear mechanism, namely tribofilm formation, there were significant differences among the tribofilms produced by different tribo-systems. Systems that released fine, oxidized metal debris (bronze-filled PTFE and/or uncoated counterpart) developed >1 μm thick, continuous tribofilms on both mating surfaces. Thickness and continuity of the tribofilm decreased with a non-wearable Cr2O3-coated counterpart and/or PEEK as a filler. The tribofilm was conducive to lower steady-state friction, but not lower wear, against stainless steel, whereas all performances (friction coefficient, specific wear rate) were levelled out with a Cr2O3-coated counterface.

Mechanochemical preparation of NiCuSn nanoparticles and composites in presence of cetyltrimethylammonium bromide (CTAB) and the catalytic application of the products in homocoupling and hydration of terminal alkynes

We report the synthesis of the NiCuSn nanoparticles and nanocomposites in mechanochemical route using CTAB as milling additive. The study of grinding intensity (frequency) and time interval drew up the importance of the well-chosen operation parameters. The mild milling resulted in formation of NiSn intermetallics, while the intense ones aided the evolution of bronze and copper(I) oxide phases. The utilization of CTAB proved to be the key factor to prevent or slow down the process of mechanical alloying and to fritter the metal grains into the nanodimensions. The dynamic light scattering data demonstrated positively charged particles with average solvodynamic diameters of around 70 nm applying intense or long-term millings. Without CTAB or with relatively short or weak grindings, these values remained between 230 and 550 nm, as in the case of the surface areas getting around 20 m2/g with and 1 m2/g without CTAB. The catalytic transformation of p-methoxyphenylacetylene in dimethyl sulfoxide showed that the copper, copper(I) oxide and bronze particles managed the reaction toward the evolution of 1,3-diyne in Glaser-Hay homocoupling without base addition, while the Sn and SnO2 phases assisted to the Markovnikov-type hydration of alkyne groups. The formation of α-diketone signed that the anti-Markovnikov route was also occurred. The use of CTAB was found to exert a profound effect on the quality of catalytic end-products through the controlled generation of bronze and tin oxide phases and the solid solution of nickel atoms.

The tribological properties and corrosion resistance of PPS/PTFE-bronze coatings deposited by electrohydrodynamic jet deposition

PPS/PTFE-bronze coatings were prepared by electrohydrodynamic jet deposition on the surface of AISI 1045 steel to improve the tribological property and corrosion resistance of the steel. Three different thicknesses of PPS/PTFE-bronze coatings were prepared to investigate the effect of coating thickness on the coating properties. The surface morphology and surface contact angle of the coatings were measured, and the looseness of the coatings was evaluated using scratch tests. The tribological property and corrosion resistance of PPS/PTFE-bronze coatings with different thicknesses were tested by reciprocating sliding dry friction experiment and electrochemical workstation, respectively. The results showed that the wear rate of the coating filled with irregular tin bronze particles at the thickness of 24 layers was 6.5 times higher than that at the thickness of 12 layers, and the corrosion current density was also doubled. This was because the number of irregular bronze particles increased as the coating thickened, making the cross-linking reaction more obstructed. As a result, the cross-linking density decreased and the coating structure became looser, leading to the decreases in the tribological property and corrosion resistance of the PPS/PTFE-bronze coatings with thickness.

Model of the cavitation wear resistance of metal powder filled epoxy composites

A powder-filled epoxy compound was tested for cavitation wear in the form of bronze particles BraZHNMc9-4-4-1. The particles were obtained by sawing a bronze bar. The composition of the compound was as follows: 100 parts of resin K-153 and 12 parts of hardener (polyethylene polyamine). The specimens were shaped as cylinders, 15.5 and 15 mm in diameter and height, respectively. The tests were carried out with an ultrasonic magnetostrictive vibrator in fresh water at water temperature 20 ± 3 ° C. The frequency and amplitude of oscillations of the vibrator hub end were approximately 22 kHz and 28 μm, respectively. The distance between the end of the concentrator and the end of the specimen wear was set to 0.5 mm. A second-order model describing the cavitation wear as a function of the bronze particle size, its content in the composite and the specific surface area of the particles was constructed by the least-squares method. The cavitation wear of the composite increases with increasing values of these parameters. The greatest influence on composite cavitation wear has the total surface area of bronze microparticles in volume unit.

Effect of the Intensity of Mechanical Processing of Bronze Particles on the Characteristics of Coatings Formed by the Method of Cold Gas-Dynamic Spraying

Effect of the Intensity of Mechanical Processing of Bronze Particles on the Characteristics of Coatings Formed by the Method of Cold Gas-Dynamic Spraying

Effect of High-Temperature Treatment of Bronze Particles on the Characteristics of Coatings Formed by the Method of Cold Gas-Dynamic Spraying

Effect of High-Temperature Treatment of Bronze Particles on the Characteristics of Coatings Formed by the Method of Cold Gas-Dynamic Spraying

Additive Manufacturing and Characterization of Metal Particulate Reinforced Polylactic Acid (PLA) Polymer Composites.

Affordable commercial desktop 3-D printers and filaments have introduced additive manufacturing to all disciplines of science and engineering. With rapid innovations in 3-D printing technology and new filament materials, material vendors are offering specialty multifunctional metal-reinforced polymers with unique properties. Studies are necessary to understand the effects of filament composition, metal reinforcements, and print parameters on microstructure and mechanical behavior. In this study, densities, metal vol%, metal cross-sectional area %, and microstructure of various metal-reinforced Polylactic Acid (PLA) filaments were characterized by multiple methods. Comparisons are made between polymer microstructures before and after printing, and the effect of printing on the metal-polymer interface adhesion has been demonstrated. Tensile response and fracture toughness as a function of metal vol% and print height was determined. Tensile and fracture toughness tests show that PLA filaments containing approximately 36 vol% of bronze or copper particles significantly reduce mechanical properties. The mechanical response of PLA with 12 and 18 vol% of magnetic iron and stainless steel particles, respectively, is similar to that of pure PLA with a slight decrease in ultimate tensile strength and fracture toughness. These results show the potential for tailoring the concentration of metal reinforcements to provide multi-functionality without sacrificing mechanical properties.