Holder Materials Research Articles

Investigation of Mechanical Properties of Ti6Al4V Alloy Foams produced by Powder Metallurgy Method

In this study, it was aimed to production titanium alloy implants, which are widely used in the biomedical industry, as foamed materials under different mechanical alloying and sintering conditions using the powder metallurgy method Tİ6Al4V alloy is good mechanical properties, good biocompatibility properties and good corrosion resistance used as hard tissue replacements and implants. Similar mechanic properties with bone are expected from the implant to work coherently for long cycles of use and without any failure. Especially, elastic modulus of implant must be similar with bones, if not, some damages at bone surface and fallowing repeats of implant surgeries are reported. This situation has a destructive effect on health, finance, and comfort of the patient/user of the implant. In this study, powder metallurgy and space holder removal methods were used to produce porous Ti6Al4V specimens. Throughout the project study different space holder materials and binder agents were used. As weight percent, 20%, 30%, 40%, 60%, 70%, 80% porous specimens were pressed at uniaxial press machine, and sintered to the 850 ºC at argon atmosphere in furnace to reduce the oxidation to the level as low as possible. The E-Modulus values of the specimens reached the desired values with increasing porosity. It was obtained as 88 MPa in the specimen with 80% porosity, decreasing inversely proportionally, especially from the 60% porosity rate.

Influence of filter holder materials on the physicochemical and antioxidant characteristics of coffee beverages

Influence of filter holder materials on the physicochemical and antioxidant characteristics of coffee beverages

Analyzing the Effects of Tool Holder Stiffness on Chatter Vibration Reduction in Turning

This paper investigates the effects of tool holder materials on chatter vibration in turning operations. The study uses a complex dynamic turning model with two degrees of freedom for the orthogonal cutting system. Tool holders made from different materials, including Al 5083, Al 6082, Al 7012, and a standard 4140 material, were subjected to chatter vibration to investigate their process damping capabilities. The study found that the standard tool holder 4140 allows for higher stable depths of cut and produces similar process damping values compared to the other tool holders. Finite element analyses (FEA) were performed to verify the experimental results, and the modal and FEA analyses produced very similar results. The study concludes that future research should investigate the effects of tool holders made from high alloy steel alloys on process damping. Overall, this paper provides important insights into the effects of tool holder materials on chatter vibration and process damping in turning operations, which can help in the design of more efficient and effective cutting systems.

A New Material Selection Method Based on Weighted Mean Values of Overall Performance Scores from Different Multicriteria Decision-Making Methods

There are many multicriteria decision-making (MCDM) methods applicable to material selection. It may produce considerable differences between the material selection results. However, it is unknown which MCDM method has more rational result and there is no rational method to determine final overall performance scores of alternative materials. We propose a new method to determine final overall performance scores and final ranks of alternative materials combined with results from different MCDM methods in material selection. The outline is as follows. First, calculate the overall performance scores and ranks of the alternative materials using some different MCDM methods. Second, calculate mean values of the rank correlation coefficients between the rankings obtained from different MCDM methods and assign the mean values as the priority weights of each MCDM method. Finally, calculate the weighted mean values of the overall performance scores obtained from different MCDM methods and determine them as final overall performance scores of the alternative materials. To illustrate the effectiveness, we apply the proposed method to select best tool holder materials. The method may help material designers and engineers to apply different MCDM methods to material selection and multi-objective optimization of material composition and process, much more effectively and actively.

Glycosylated MoS2 Sheets for Capturing and Deactivating E. coli Bacteria: Combined Effects of Multivalent Binding and Sheet Size

AbstractMolybdenum disulfide (MoS2) holds great promise for antibacterial applications owing to its strong photothermal performance and biocompatibility. Most of its antibacterial explorations have sought enhanced antibacterial potency through designing new hybrid inorganic materials, the relationship between its physiochemical properties and antibacterial activities has yet to be explored. This work is the first to investigate the combination effects of different sized and functionalized MoS2 sheets on their antibacterial activities. The bacterial capture abilities of 3 µm mannosylated, galactosylated, and glucosylated sheets, as well as 300 nm mannosylated sheets, all with similar sugar densities, are compared. Only mannosylated MoS2 sheets are found to agglutinate normal Escherichia coli (E. coli) and large mannosylated MoS2 sheets show the strongest E. coli agglutination. Despite slightly weaker photothermal performance under near‐infrared (NIR) laser irradiation, large mannosylated MoS2 sheets exhibit higher antibacterial activity than the smaller sheets. By much stronger specific multivalent binding, large sheets capture E. coli more efficiently and compensate for their reduced photothermal activity. Besides providing a facile approach to eliminate E. coli bacteria, these findings offer valuable guidance for future development of 2D nanomaterial‐based antibacterial agents and filter holder materials, where large‐functionalized sheets can capture and eliminate bacteria powerfully.

Experiment study on damping characteristics of the turning tool holder materials

In general machine tool vibration that occurs during any metal cutting operation or machining process. These vibrations increase the temperature of the cutting tool in additional which ultimately causes the reduction of cutting tool life. In this study two types of materials (Copper and Brass) were used as a damping material to decrease cutting tool vibration and cutting tool tip temperature. The structural modification was made in the normal cutting tool holder to provide the additional damping effects during the metal cutting operation. A new damped turning tool holder was fabricated by fitting these materials to improve the stability of the cutting tool holder. The standard and recommended levels of input parameters like cutting speed, feed rate, depth of cut and overhang length of the tool were selected for experimental works. The influence of input parameters was investigated for various cutting conditions. From the result, the optimum conditions and desired outcome was obtained with the damped turning tool holder also considerably vibration control was achieved during turning operation.

Using Planar Laser Induced Fluorescence and Micro Particle Image Velocimetry to study the heating of a droplet with different tracers and schemes of attaching it on a holder

The Planar Laser Induced Fluorescence optical technique is used to measure the droplet temperature field, and the Micro Particle Image Velocimetry – the velocities of natural convection in the droplet. We focus on the convection, vortex formation centers, convection velocities, and the influence of convection on the temperature in different droplet sections. The most common tracer particles are used (Al2O3, TiO2, polyamide). Differences in the temperature fields of evaporating droplets with tracers and without them are analyzed. We compare the reliability of measuring droplet temperature using Planar Laser Induced Fluorescence and fast-response thermocouples. The concentrations of tracers are varied to establish the ranges in which the fields of temperature and convection velocities can be reliably measured in rapidly heated and evaporating droplets. We study the influence of typical holder materials on droplet heating rates. Metal rods, wires, and nichrome wires are used. The focus is on illustrating the influence of the holder type and material on the droplet temperature field, its heating and evaporation rates, as well as its lifetime. We consider typical schemes of droplet fixation on holders, as well as the main differences in the fields of temperature and convection velocities in different droplet sections. As a result, we have obtained the concentrations of Al2O3 and TiO2 tracers that make it possible to use both Planar Laser Induced Fluorescence and Micro Particle Image Velocimetry at the same time. Examples are given of particle agglomeration and photobleaching. The use of polyamide particles as tracers is found not feasible for evaluating the convection rates in droplets, because they are displaced from the deep layers of a droplet to the surface. It is established that if a Rhodamine B solution contains Al2O3 and TiO2 tracers, the fluorophore settles on those particles, which may degrade the accuracy of temperature measurement using Planar Laser Induced Fluorescence. The experimental findings are important to develop the fields of research into the conditions and characteristics of heating droplets, films, and liquid jets, using Planar Laser Induced Fluorescence and Micro Particle Image Velocimetry.

Effect of Space Holder Size on the Porous High Purity Aluminum Property

Porous high purity aluminum was fabricated using a powder metallurgy route combined with the space holder technique. The high purity aluminum powder was mixed with three different particle sizes and contents of the space holder material. The mixed powders were cold compacted at 400 MPa and sintered at 550 °C. The effects of space holder size on the microstructure and mechanical properties of porous high purity aluminum were systematically studied. Results revealed that the size and content of the space holder materials have a significant effect on the mechanical properties of porous aluminium. The compressive strength and hardness of the porous aluminum increased as the size and amount of the space holder material increased and decreased, respectively. The thickness of the cell wall increased with an increase particle size of the space holder material.

Development of a sample holder for synchrotron radiation-based computed tomography and diffraction analysis of extraterrestrial materials.

A sample holder for a suite of synchrotron radiation measurements on extraterrestrial materials, which are fragile and irregularly shaped, was developed using carbon nanotubes and polyimide. The holder enables investigation of such samples with multiple analytical instruments, which means that we can reduce the number of sample transfers between holders. The holder developed in our study also enables investigation of such samples without exposure to the terrestrial atmosphere, which contains abundant contaminants, such as water vapor and organic substances. The stability of the samples in the holder during the measurements and disturbance of the analysis result by the holder were evaluated, which showed that sample drift motion and image disturbance due to x-ray attenuation and scattering of the holder materials are insignificant.

Intercomparison of Indoor Radon Measurements Under Field Conditions In the Framework of MetroRADON European Project.

Interlaboratory comparisons are a basic part of the regular quality controls of laboratories to warranty the adequate performance of test and measurements. The exercise presented in this article is the comparison of indoor radon gas measurements under field conditions performed with passive detectors and active monitors carried out in the Laboratory of Natural Radiation (LNR). The aim is to provide a direct comparison between different methodologies and to identify physical reasons for possible inconsistencies, particularly related to sampling and measurement techniques. The variation of radon concentration during the comparison showed a big range of values, with levels from approximately 0.5 to 30 kBq/m3. The reference values for the two exposure periods have been derived from a weighted average of participants’ results applying an iterative algorithm. The indexes used to analyze the participants’ results were the relative percentage difference D(%), the Zeta score (), and the z-score (). Over 80% of the results for radon in air exposure are within the interval defined by the reference value and 20% and 10% for the first and the second exposure, respectively. Most deviations were detected with the overestimating of the exposure using passive detectors due to the related degassing time of detector holder materials.

Effects of sample holder characteristics on thermal diffusivity measurement using the laser flash method

The laser flash method is commonly adopted to measure the thermal diffusivity of solid material since its advantages, such as a wide measuring range of thermal diffusivity, a small amount of samples, a high measuring temperature, and so on. However, the sample holders used by this method are limited and costly, which seriously affects the convenience and economy of this method. So, in order to develop and design more kinds of sample holders, it is necessary to study the effects of sample holder characteristics on measuring results. A transient flow and heat transfer calculation model was developed to analyse effects of pulse energy, pulse time, laser beam area, protective gas flow and sample holder materials on the thermal diffusivity measurement. It is found that the temperature increase of the sample upper surface ΔT obviously increases with pulse energy, pulse time and laser beam area increasing, but the half heating up time t50 slightly decreases with theses parameters increasing. ΔT and t50 are independent to the volume flow rate of protective gas. The heat transfer process and mechanism between sample and holders with various materials were analysed. The heat loss of samples depends on the heat conduction and radiation between sample and holder, the heat convection and radiation from sample to protective gas. The thermal conductivity, specific heat and emissivity of holder materials can affect the heat conduction and radiation between sample and holder slightly. So the ΔT and t50 are nearly independent to the holder material properties. Based on these conclusions, a new SUS310 holder was made, and the thermal diffusivity of a sample was experimentally measured using the new holder. As a result, the measuring error is less than ±3%.

Preparation of foamed aluminum and its application in China

As a new structural material combined with functional characteristics, aluminum foam possesses low density, high specific surface area and stiffness, good sound and energy absorption, as well as excellent electromagnetic shielding. Among the preparation ways which can be used to fabricate aluminum foam, the methods, such as direct foaming in aluminum melt, melt foaming by gas injection, powder metallurgy route and casting around space holder materials, may be the main ones. The R & D of the methods above in China is discussed in this paper. Aluminum foams have been exploited in road noise barrier, buildings, rail transit vehicles, aerospace and bridge protection in China nowadays. The applications of aluminum foams obtained by some methods are also emphatically described. It is speculated that the application fields and amount of the aluminum foams may be increased in the future along with the further development of Chinese economy.

Child droplets produced by micro-explosion and puffing of two-component droplets

This paper provides the results of an experimental study of child droplet distribution by size when a group of factors (heating temperature, parent droplet sizes, component concentration, holder materials) influence the heat exchange between the droplets and the heating environment on three setups with different geometries and characteristics (with heated substrate, hot air flow and muffle furnace). Two types of compositions have been considered: two-component droplets without intermixing and droplets of prepared emulsions with distributed microvolumes of water. The following combustible components were used: Diesel, petroleum oil, gasoline, rapeseed oil, and kerosene. It has been determined that with a heated substrate, the number of child droplets is significantly higher, and the time of heating is significantly shorter than in the schemes with a hot air flow and a muffle furnace. The dimensions of droplets largely depend on the amount of combustible liquids and the type of initial droplet: mixed or immiscible. It has been shown that for each composition there is a critical size of the initial droplet, for which the number of child droplets is at its maximum.

Creating emergent phenomena in oxide superlattices

Complex oxides are record holder materials for many phenomena, including ferroelectricity, piezoelectricity, superconductivity and multiferroicity. Complex oxides often have competing ground states with energies slightly higher than that of the true ground state. This competition is fortuitous because thermodynamic variables (for example, temperature, electric field, magnetic field, stress and chemical potentials) can access these metastable phases that are usually hidden but emerge as the energetic landscape is reshaped by adjusting the thermodynamic variables. Epitaxial superlattices are a platform for imposing thermodynamic boundary conditions to unleash the properties of hidden phases by altering the delicate balance between competing spin, charge, orbital and lattice degrees of freedom. Additionally, a feature of complex oxides with large responses (large property coefficients) is the coexistence of phases on the nanoscale. New phases can emerge at the heterointerfaces of oxide superlattices, and X-ray, electron, neutron and proximal probes as well as ab initio theoretical studies can provide insights into these emergent phenomena. Oxide superlattices reveal emergent phenomena if the balance between competing degrees of freedom is altered. In this Review, synthetic approaches to tap the properties of competing ground states are described, focusing on two examples — one example yielding a room-temperature multiferroic and a second producing polarization skyrmions.

An Experimental Study on Boron Carbide Reinforced Open Cell Aluminum Foams Produced via Infiltration Technique

Light structures and parts are very effective for new engineering applications. Their considerably low densities, high energy absorption capabilities, and desirable mechanical properties make them useful for particularly automotive, defense and aerospace industries. Besides these positive properties, it is known that the production and processing of cellular materials is very tough and worth the effort. Recently, with advances in new technologies like 3D printing or selective laser melting, now different types of cellular materials can be produced. But manufacturing of metallic foams via casting especially replication or infiltration method is fairly an economic method when compared with other methods. In this study, vacuum-gas infiltration set-up was used to produce B4C reinforced aluminum foams. The mentioned method involves the addition of space holder materials and a dissolution technique to remove them after solidification of the metal. As space holder materials NaCl particles were selected and mixed with B4C powders to produce B4C reinforced A360 aluminum foam. By changing the weight ratio of B4C particles, the alteration of properties like porosity, compression strength, and energy absorption capacity was investigated. Additionally, computer tomography views were obtained to see and interpret the microstructures of the foams. Compression tests were carried out to evaluate the mechanical behavior of the foams under static loading. The porosities of samples obtained as between 65-75%. The compressive strength increased with rising relative density.

Impact of Holder Materials on the Heating and Explosive Breakup of Two-Component Droplets

The heating of two-component droplets and the following explosive breakup of those droplets have been extensively studied over the most recent years. These processes are of high interest, since they can significantly improve the performance of many technologies in fuel ignition, thermal and flame liquid treatment, heat carriers based on flue gases, vapors and water droplets, etc. Research throughout the world involves various schemes of droplet heating and supply (or, less frequently, injection) to heating chambers. The most popular scheme features the introduction of a two-component or multi-component droplet onto a holder into the heating chamber. In this research, we study how holder materials affect the conditions and integral characteristics of droplet heating and explosive breakup: heating time until boiling temperature; minimum temperature sufficient for droplet breakup; number and size of fragments in the resulting droplet aerosol, etc. Experiments involve droplets that are produced from flammable (oil) and non-flammable (water) components with significantly different thermophysical and optical properties, as well as boiling temperature and heat of vaporization. The most popular elements with the scientific community, such as ceramic, steel, aluminum, copper, and phosphorus rods, as well as a nichrome wire, serve as holders. We establish the roles of energy inflow from a holder to a droplet, and energy outflow in the opposite direction. We compare the holder results with a supporting thermocouple, recording the drop temperature under a heat transfer provided at 350°C. Finally, we forecast the conditions that are required for a significant improvement in the performance of thermal and flame water treatment through the explosive breakup of two-component droplets.

93Zr developments at the Heavy Ion Accelerator Facility at ANU

The long-lived radionuclide 93Zr t1/2 = (1.61 ± 0.05) Ma plays an important role in nuclear astrophysics and nuclear technology. In stellar environments, it is mainly produced by neutron capture on the stable nuclide 92Zr. On Earth high amounts of radioactive 93Zr are produced in nuclear power plants directly from 235U fission, but also by neutron capture on 92Zr, as Zr-alloys are commonly used as cladding for nuclear fuel rods.Despite its importance, the neutron capture cross section of 92Zr at thermal and stellar energies (keV) is not well known. Neutron irradiation of 92Zr and subsequent determination of produced 93Zr via AMS is a promising approach to resolve this issue. The main challenge in AMS measurements of 93Zr is the interference from the stable isobar 93Nb. The high particle energies available with the 14UD tandem accelerator at the Australian National University are ideal to tackle this challenge. Different sample materials, molecular ion species and sample holder materials were tested for their 93Nb background. Commercial ZrO2 powder irradiated with thermal neutrons from the reactor at the Atominstitut in Vienna (ATI) was used as reference material for AMS measurements. In contrast to literature reports and γ-activity measurements of 95Nb, which suggest that chemical Nb reduction works, elevated 93Nb contents were measured in chemically pre-treated samples. The reasons are under investigation. At the ANU we developed AMS for ∼210 MeV 93Zr ions using an 8 anode ionisation chamber. We achieved background levels of 93A/Zr ∼ 10−12 with acceptance of 2–8% of the 93Zr ions at the high-energy side. This is more than an order of magnitude better than previously reported. The 93Nb isobar was suppressed by a factor between 13,000 and 90,000 in the detector.This performance allows measurements of the thermal and stellar neutron-capture cross section of 92Zr for samples irradiated at the ATI and the Soreq Applied Research Accelerator Facility, respectively, using AMS.

Mechanical properties and electrochemical behavior of porous Ti-Nb biomaterials.

Ti-Nb-based alloys - with their superior mechanical properties and biocompatibility - are attractive biomaterials for orthopedic implants. By producing this alloys with a porous structure, it is possible to achieve mechanical properties similar to that of bone and to facilitate cellular activities. In this study, Ti16Nb (wt%) alloys containing porosity between 4.05-% and 60.79-% were produced by powder metallurgy using different amounts of space holder materials. The samples were sintered at 1200 °C for 3 h in a high-level vacuum. The effects of the space holder content - in terms of mechanical properties, amount and morphology of the pores, density and the corrosion behavior of the Ti16Nb alloy - were investigated. It is seen that the addition of 70 vol% space holder materials to the Ti16Nb alloy leads to a decrease in the density value from 4.67 g/cm3 to 1.91 g/cm3. Also, it is observed that by producing Ti16Nb with 70 vol% space holder, elastic modulus, compressive and transverse rupture strength values decreased from 96 GPa to 15 GPa, from 1450 MPa to 100 MPa, and from 1173 MPa to 97 MPa, respectively. Although Ti16Nb porous alloys are designed by imitating the properties of the cortical bone for use in the production of load-bearing implants, it is seen that increasing the amount of pores causes, an increase in the corrosion rate and the corrosion current density and a decrease in the polarization resistance.

Titanium Foams Processed Through Powder Metallurgy Route Using Lubricant Acrawax as Space Holder Material

In the present work titanium foams have been synthesized using acrawax as the space holder material. Acrawax has generally been used as a lubricant for easier compaction of aluminium alloy powders. This study deals with the use of this space holder material in the form of beads for creating pores in titanium metal matrix. Acrawax facilitates the formation of continuous dense cell walls which is difficult to obtain using ordinary space holder materials. Moreover, acrawax is compressible in nature and it facilitates the formation of better and uniformly sized pores. Titanium foams have been synthesized utilizing acrawax in two different sizes. The effect of using differently sized acrawax on the cell walls and mechanical properties has also been carried out in this study.

Processing of open-pore silicon foams using graphite composite as space holder

In this study, a novel space holder is used for the fabrication of Si foams. The space holder is a graphite composite (GC) with regular spheroidal cells. Conventional space holder materials are not suitable for casting Si foams. The main issue in this context is the differences between the melting point of the foam's base material and the one of common space holders. GC offers many advantages as e.g. low cost, good dissolution by oxidation, high melting point and non-toxicity. This type of space holder is chemically stable when being in contact with liquid and solid Si, and it is, hence, suitable for a melt metallurgical processing route. Si foams are manufactured by applying replication casting. The resulting foam geometry and its surface are analyzed using LM and SEM. XRD measurements are performed to investigate the quality of the Si foam in terms of contamination by graphite or oxygen.