Types Of Metal Powders Research Articles

Biological Effects and Toxicity of Compounds Based on Cured Epoxy Resins.

The aim of this work was to investigate selected biological and toxicity properties of cured epoxy resin-based compounds based on a bisphenol A epoxy resin, cold-cured by a polyamide and containing two types of metal powders (aluminum and copper). This study involved cytotoxicity analysis, pH measurements, absorbance measurements and sterilization. The cytotoxicity analysis was conducted to determine the harmful degree of the cured epoxy resin. Aimed at identifying toxic agents in cured compounds, the cytotoxicity analysis involved absorbance measurements in an entire wavelength range. Cytotoxicity and absorbance results demonstrated that the extracts of all the tested resin samples had no cytotoxic effects on the cells of living organisms. The absorbance values obtained over the entire wavelength range did not point to the formation of aggregations, which proved that no toxic agents harmful to living organisms were extracted from the resin samples. Based on the results obtained, it can be concluded that all tested compounds, based on epoxy resins, which are also used as adhesives in various applications, are essentially safe materials when using such formulations in a cured state.

Kekerasan Produk Metalurgi Serbuk Berbahan Limbah Aluminium dengan Metode Kompaksi Bertahap

The product resulting from the powder metallurgy process has advantages in terms of mechanical properties and physical properties. Material engineering by mixing several types of metal powders is very possible to do. The composition of this powder metallurgical process material is a mixture of aluminum powder (80%), copper powder (15%) and silicon carbide powder (5%) by weight then compacted with a compaction load gradually, starting with a load of 3 tons, holding for 3 minutes, followed by a load of 3 tons. 4 tons were held for 3 minutes and the last 5 tons were held for 3 minutes by pre sintering 1250C. Sintering in the kitchen with temperature variations of 4500C, 5000C and 5500C and sintering time for 60 minutes. Tests carried out on the specimens were hardness tests using the Rockwell (HRF) method. The results showed that the hardness of a single material has a hardness of around 35 HRF. The average hardness of the mixed material at a sintering temperature of 4500C is 80 HRF. The hardness of the mixed material at a sintering temperature of 5000C on average is 74 HRF. Meanwhile, the hardness of the mixed material at a sintering temperature of 5500C averaged 52 HRF. It can be concluded that the application of heat at the time of compaction and the selection of the sintering temperature greatly affect the hardness of the product resulting from the powder metallurgy process.

Defects in Metal Components Produced by Selective Laser Melting

Defects in parts produced from metal powder by selective laser fusion are studied. Typical defects are presented for this method. They do not depend on the type of metal powder but rather on the chemical composition and purity of the initial material.

A study on the preparation method of vaporized amplification sheets and electron beam machining characteristics

An electron beam was used to mainly utilize for polishing, finishing, welding, a lithography process, etc. However, the drilling process does not develop in the country because it is difficult to make high power parts and backing materials. The backing materials are one of the important factors and decided the quality of machined micro holes according to the constituents. This study considers the preparation of vaporized amplification sheets and the analysis of key factors for improving the electron beam processability and efficiency. We evaluated the defoaming process (for removing pores from the sheets), distribution, processability and hole shape (all based on the type of metal powder), and thermal characteristics (based on the type of silicon). Also, we identified process parameters for the optimization of the electron beam machining process.

Improved Corrosion Resistance of Selective Laser Melted Ti–5Cu Alloy Using Atomized Ti–5Cu Powder

The different types of metal powder used for selective laser melting (SLM) process would cause distinct corrosion behavior due to the uniformity of the obtained microstructure. The SLM-produced Ti–5Cu alloy using atomized Ti–5Cu metal powder (SLMed Ti–5Cu) in this work reveals a relatively uniform microstructure with overwhelming acicular α/α′ phase and shows great advantages on corrosion resistance compared with the SLM-produced Ti–5Cu alloy using the mixture powder (SLMed-M Ti–5Cu). The effect of the micro-galvanic cells decreases due to the undetectable Ti2Cu phase in the microstructure of the SLMed Ti–5Cu. An apparent passivation behavior was observed for SLMed Ti–5Cu instead of severe pitting phenomenon for the SLMed-M Ti–5Cu. The charge transfer resistance of SLMed Ti–5Cu in this work is 10.09 ± 2.63 MΩ cm2, which is significantly higher than that of SLMed-M Ti–5Cu (4.76 MΩ cm2). The above result indicates the atomized Ti–5Cu powder plays an important role in the formation of the uniform microstructure of SLMed product, thereby enhancing its corrosion resistance in Hank’s solution at 37 °C.

A Study on Micro-Structure and Wear Behavior of AISI M4 and CPM15V Deposited by Laser Melting

AISI M4 and CPM15V are used as tool steels since they have high hardness and wear resistance. This study is concerned with die and mold hardfacing using laser melting deposition with M4 and CPM15V powders. For this purpose, the two types of metal powders were deposited on SKD11 base metal, and the microstructures, hardness and wear resistance of the deposited materials were compared. During processing, substrate preheating was used to reduce the degree of thermal deformation and prevent crack formation. Based on the preliminary experiments, the process conditions were established. As a result of observing of the microstructure, columnar and cellular dendrites were observed in the M4 deposited layer. Using EDS analysis, the carbides precipitated along grain boundaries were identified to be M6C/M23C6 carbides with a high content of molybdenum and tungsten. On the other hand, no dendritic microstructures were observed in the CPM15V deposited layer, and metastable austenite, martensite, and M8C7 carbides were formed. A large amount of fine carbide was found to have a high content of vanadium and chromium. The M4 and CPM 15V deposited regions had average hardnesses of 815 and 897 HV, respectively. The ball-on-disc test results showed that the deposited CPM15V had better wear resistance than that of the M4 deposited. These results are attributed to high martensite fraction, and the types and sizes of carbides of the deposited CPM15V. Key words: AISI M4, CPM15V, laser melting deposition, hardness, wear

The Effect Of Adding Metal Powders To the Spot Welded Area Of Dissimilar Metals

The process of spot welding has been and remains one of the most important manufacturing processes; the vehicle industry requires the use of this process frequently. To reduce the cost and improve the quality of the products in some applications, it was necessary to weld different metals, and due to the different specifications of welded metals it is necessary to study this situation and try to improve the specifications of the welding area. In this work, 304 stainless steels and SAE1006 was spot welded at different weld current and welding duration values because of their wide use. The aim of this research is improve the welding zone mechanical characteristics and reduce the amount of energy used by using two different types of metal powders have acceptable resistivity which added to the welding area to prevent thermal energy from dissipating rapidly allowing for a stronger bonding, This addition helped to create an extra bond between the base metal and metal powder which improved the mechanical properties of the nugget. It was found that increasing the amount of weld current and welding duration improved the mechanical features of the welding area, and from the results it was clear that the effect of the addition of titanium powder was more effective than nickel powder.

Development of Experimental Setup of Metal Rapid Prototyping Machine using Selective Laser Sintering Technique

Unlike in the traditional manufacturing processes, additive manufacturing as rapid prototyping, allows designers to produce parts that were previously considered too complex to make economically. The shift is taking place from plastic prototype to fully functional metallic parts by direct deposition of metallic powders as produced parts can be directly used for desired purpose. This work is directed towards the development of experimental setup of metal rapid prototyping machine using selective laser sintering and studies the various parameters, which plays important role in the metal rapid prototyping using SLS technique. The machine structure in mainly divided into three main categories namely, (1) Z-movement of bed and table, (2) X–Y movement arrangement for LASER movements and (3) feeder mechanism. Z-movement of bed is controlled by using lead screw, bevel gear pair and stepper motor, which will maintain the accuracy of layer thickness. X–Y movements are controlled using timing belt and stepper motors for precise movements of LASER source. Feeder mechanism is then developed to control uniformity of layer thickness metal powder. Simultaneously, the study is carried out for selection of material. Various types of metal powders can be used for metal RP as Single metal powder, mixture of two metals powder, and combination of metal and polymer powder. Conclusion leads to use of mixture of two metals powder to minimize the problems such as, balling effect and porosity. Developed System can be validated by conducting various experiments on manufactured part to check mechanical and metallurgical properties. After studying the results of these experiments, various process parameters as LASER properties (as power, speed etc.), and material properties (as grain size and structure etc.) will be optimized. This work is mainly focused on the design and development of cost effective experimental setup of metal rapid prototyping using SLS technique which will gives the feel of metal rapid prototyping process and its important parameters.

Influence of Gas Type on the Thermal Efficiency of Microwave Plasmas for the Sintering of Metal Powders

Microwave plasmas have enormous potential as a rapid and energy efficient sintering technology. This paper evaluates the influence of both plasma atmosphere and metal powder type on the sintering temperatures achieved and the properties of the sintered powder metal compacts. The sintering is carried out using a 2.45 GHz microwave-plasma process called rapid discharge sintering (RDS). The sintering of three types of metal powder are evaluated in this study: nickel (Ni), copper (Cu) and 316L stainless steel (SS). An in-depth study of the effects of the plasma processing parameters on the sintered powder compacts are investigated. These parameters are correlated with the mechanical performance of the sintered compacts to help understand the effect of the plasma heating process. The substrate materials are sintered in four different gas discharges, namely hydrogen, nitrogen oxygen and argon. Thermocouple, pyrometer and emission spectroscopy measurements were taken to determine the substrate and the discharge temperatures. The morphology and structure were examined using scanning electron microscopy and X-ray diffraction. The density and hardness of the sintered compacts were correlated with the plasma processing conditions. As expected higher densities were obtained with powders with lower sintering temperatures i.e. nickel and copper when compared with stainless steel. Under the power input and pressure conditions used, the highest substrate temperature attained was 1,100°C for Cu powder sintered in a nitrogen atmosphere. In contrast under the same processing conditions but in an argon plasma, the temperature achieved with SS was only 500°C. The effect of the plasma gas type on the sintered powder compact chemistry was also monitored, both hydrogen and nitrogen yielded a reducing effect for the metal in contrast with the oxidising effect observed in an oxygen plasma.

A new test method for measuring the galling resistance between metal powders and die tool materials in powder compaction

The friction characteristics and galling resistance between metal powder and die tool material in metal powder compaction is of outmost importance since they will influence the porosity and surface quality of the green body and consequently the porosity, tolerances and surface quality of the final sintered product. In the present study, a new test method for evaluating the tribological performance of die tool materials aimed for powder compaction is presented. The test method is based on controlled scratch testing using a commercial scratch tester but instead of the commonly used Rockwell C diamond stylus a sample holder with a small green body of compacted powder particles is drawn over the surface in a well controlled multi pass linear reciprocating sliding contact. The capability of the test method was evaluated for different types of tool materials including two PVD coatings in contact with different types of metal powders to determine the friction characteristics and the adhesion and material transfer tendency at the sliding interface. Post-test examination of the tool surfaces using FEG-SEM and EDS were performed in order to evaluate the mechanisms controlling the friction behavior and the material transfer tendency. The results show that the proposed test is a simple and fast method to obtain relevant data regarding the friction and galling characteristics of die tool materials in metal powder compaction. The mechanisms prevailing at the green body/die tool material interface, e.g. cold welding, can easily be monitored by the friction and acoustic emission signals. Of the die tool materials investigated the low friction PVD a-C:Cr coating displayed the lowest friction and highest galling resistance.

Monitoring of metal powder by eddy current

Nanocrystalline Fe(1−x)Cox, Fe, Fe80N120,Cu70Fe18Co12 mixtures have been prepared by mechanical alloying using a planetary ball mill under several milling conditions. Their structures and magnetic properties were investigated. Mechanical alloying is a non-balanced process for synthesis materials. The structural effects of mechanical alloying of powders were investigated by scanning X-ray diffraction analysis. In this report, we examine the applicability of eddy current techniques in-process for monitoring of powder density particle size and the time necessary to structure variation. An eddy current based monitoring system developed to measure metal powder density is expanded for monitoring metal powder diameter in metal compounds. Experimental sensor readings were gathered using four different metal powders with known particle sizes Fe(1−x)Cox, Fe, Fe80N120 and Cu70Fe18Co12. Analysis of the data showed that the sensor output was in relation with different parameter of powder (diameter, density and structure) that the sensitivity of the sensor differed with the type of metal powder. The merit of this technique is its reliance on a simple and inexpensive sensor probe.

Study on safe air transporting velocity of nanograde aluminum, iron, and titanium

The process of delivering nanograde metal powders by a high-speed carrier gas is often subject to high explosion risks. This study adopted initial flow rates of 13.1, 8.5, 6.5, and 3.5 m/s for air transporting 30-nm titanium powder, 35-nm iron powder, and 35-nm aluminum powder to gauge the impact on a pipe bend in a 20-l-apparatus. The test results revealed that the 30-nm titanium powder caused an explosion at all initial flow rates; the 35-nm iron powder also caused an explosion, but dust explosion and sintering were eliminated when the flow rate was adjusted to less than 3.5 m/s; and the 35-nm aluminum powder exhibited no explosion or sintering at all flow rates. When pure nitrogen was used for transporting nanograde metal powders, no explosions occurred for all the three types of metal powders. The minimum ignition energy for these three types of nanograde metal powders was less than 1 mJ.

Effects of process parameters on surface morphology of metal powders produced by free fall gas atomization

There are a number of process parameters which affect the characteristics of metal powders produced by free fall gas atomization. In the following work effects of various process parameters like apex angle of atomizer, focal length of atomizer, number of nozzles, diameter of nozzles, diameter of liquid metal delivery tube, superheat of liquid metal and type of metal etc. were studied on their surface morphology. It was observed that shape of powder particles depends on apex angle, superheat of liquid metal, type of metal and particle size range within a powder collective. Other parameters like focal length of atomizer, number of nozzles, diameter of nozzles and diameter of liquid metal delivery tube were found to have no effect on the shape of powder particles. However, Surface porosity and solidification shrinkage were observed on almost all types of metal powders.

Combustion Prevention of Iron Powders by a Novel Coating Method

AbstractThe effectiveness of a novel coating method in providing fine iron powder particles with a protective barrier against rapid oxidation was systematically studied. Particles were individually coated with an alumina‐based (Al2O3) ultra‐thin film using the Atomic Layer Deposition method. The oxidation resistance of the coating layer was found to be greatly dependent on the film thickness. Furthermore, for each film thickness there was a corresponding temperature above which the film drastically lost its protective effectiveness, primarily due to cracking caused by the thermal expansion mismatch between the particle and the alumina film. This problem was largely overcome when, instead of Al2O3, the protective film was generated from alternating layers of Al2O3/ZnS to ensure that the thermal expansion properties of the resultant film matched that of iron. The technique employed in this study is quite robust and can be adapted for combustion prevention in other types of metal powders.

Characteristics of mixed hydrogen storage electrode

Abstract Mixed hydrogen storage electrodes were made of hydrogen storage alloy powder M L Ni 3.75 Co 0.55 Mn 0.42 Al 0.27 (M L denotes La-rich mischmetal) mixed with powder of other components. The changes of the electrochemical characteristics of hydrogen storage electrodes were investigated. In this paper, we studied mixed hydrogen storage electrodes modified by various types of metal powders. The results showed that the electrochemical characteristics of hydrogen storage electrodes modified by metal powders such as Co, Ni, Mo and W were improved.

Injection moulding of silicon-iron alloys for magnetic applications : F.David, Y.Leroy. (Impac Technologies, Cormelles-le-Royal, France.)

Metal Injection Molding (MIM) is a technology by which metal products of high density and complex shape can be mass produced in a cost-effective manner. The density and particle size of metal-powder throughout the compound must be monitored if uniform products are to be obtained.In this report, we examine the applicability of eddy-current techniques to in-process monitoring of powder density and particle size. An eddy-current based monitoring system developed by the authors to measure metal-powder density is expanded for monitoring of metal-powder diameter in metal compounds. Experimental sensor readings were gathered using three different metal powders with known particle sizes: aluminum-lithium alloy (AA8090), nickel-iron magnetic alloy (PB-47) and stainless steel (SUS316L). Analysis of the data showed that the sensor output was proportional to the powder diameter under wet conditions with thermoplastic binder of constant density, and that the sensitivity of the sensor differed with the type of metal powder. The merit of this technique is its reliance on a simple and inexpensive sensor probe.

Simulation of metal powder compaction, for the development of a knowledge based powder metallurgy process advisor

The powder compaction simulations described in this paper have been performed to demonstrate suitable modelling techniques for the development of a knowledge-based system (KBS), capable of analysing proposed geometries of powder metallurgy (PM) compacts, (i.e. pre-sintered shapes formed from metal powders). The long-term aim is for the system to analyse and if necessary modify, the geometry of the compact and then generate process recommendations specifying settings for production parameters such as the required compaction pressures and punch geometries and motions. Following a review of the mechanisms of compaction, a method is presented for quantifying the deformation of adjacent spherical particles, in order to estimate the volume change which would result from compaction of particular types of metal powders. However, the applicability of such models is limited, because in practice friction between the powder and the die wall reduces the pressure, producing a non-uniform density distribution in the compact. This effect is modelled through use of a finite-element (FE) simulation, which employs a porous metal plasticity compaction model. The relevant equations are solved using the ABAQUS™ proprietary FE package, in order to generate data relating the compaction pressure to the tool displacement for a PM component. Experimental data has been generated through the uniaxial compaction of water-atomised bronze powder. Regression analysis was employed to compare this data to the model output data, a close correlation being obtained. The long-term aim is to use FE techniques to develop a range of example cases for powder compaction. Such a case-based reasoning approach offers the potential for the proposed KBS to advise on the affects of variations in compaction parameters on the density and therefore the properties, of PM compacts. This work is intended to form one of the elements of a KBS for PM currently under development, to advise on the design and process technology for the production of components by means of powder metallurgy.

Monitoring of metal-powder diameter by eddy-current sensor

Metal Injection Molding (MIM) is a technology by which metal products of high density and complex shape can be mass produced in a cost-effective manner. The density and particle size of metal-powder throughout the compound must be monitored if uniform products are to be obtained. In this report, we examine the applicability of eddy-current techniques to in-process monitoring of powder density and particle size. An eddy-current based monitoring system developed by the authors to measure metal-powder density is expanded for monitoring of metal-powder diameter in metal compounds. Experimental sensor readings were gathered using three different metal powders with known particle sizes: aluminum-lithium alloy (AA8090), nickel-iron magnetic alloy (PB-47) and stainless steel (SUS316L). Analysis of the data showed that the sensor output was proportional to the powder diameter under wet conditions with thermoplastic binder of constant density, and that the sensitivity of the sensor differed with the type of metal powder. The merit of this technique is its reliance on a simple and inexpensive sensor probe.