rss_2.0Powder Metallurgy Progress FeedSciendo RSS Feed for Powder Metallurgy Progress Metallurgy Progress 's Cover Based Soft Magnetic Composite Material Prepared By Injection Molding<abstract> <title style='display:none'>Abstract</title> <p>Soft magnetic composite materials consisting of FeSi powder and polypropylene were prepared by the injection molding method, with different polypropylene contents of 25, 30 and 35 vol. %. The magnetic and electrical properties as well as the structure of the composites were investigated. The samples exhibited very low porosity, high electrical resistivity, relatively low coercivity, sufficient saturation magnetic flux density and permeability, and high resonant frequency. FeSi particles were found to be well insulated from each other and homogeneously dispersed in the polymer matrix of the composite. The observed isotropic structure was confirmed by the fitting of the experimental dependence with the analytical expression of the reversible relative permeability vs. magnetic flux density.</p> </abstract>ARTICLE2022-04-13T00:00:00.000+00:00Synthesis of Fe-Based Alloy Reinforced with Chromium Carbide Via Sintering of Iron-Ferrochrome Powder Mixture<abstract> <title style='display:none'>Abstract</title> <p>The results of the investigation of the structure, phase composition, and properties of the alloy sintered from a mixture of iron (65 %) and high-carbon ferrochrome (35 %) powders are presented in the article. It was shown that sintering of the consolidated specimens results in a substantially heterogeneous structure consisting of two predominant phases: austenitic phase and double ferrochrome carbide. A mechanism is proposed for the dissolution of ferrochrome particles in the iron matrix as follows: M7C3 → M3C (1000÷1150 ºС) → M7C3 (1200÷1250 ºС).</p> </abstract>ARTICLE2022-04-13T00:00:00.000+00:00Influence of the Ferromagnetic Component on the Magnetic Properties of Polymer-Matrix Soft Magnetic Composites<abstract> <title style='display:none'>Abstract</title> <p>The paper presents the study of the influence of different ferromagnetic powders on magnetic properties of polymer-matrix soft magnetic composites. Samples were prepared from pure Fe and Permalloy powders with the same amount of resin and by the same technological process. The coercivity, the real part of complex permeability, saturation magnetic polarization, hysteresis loops and total energy losses and their components were investigated. It was found that the coercivity, DC losses, classical losses, excess losses and thus the total energy losses of composites depended on intrinsic magnetic properties and/or on the size and shape of ferromagnetic powder particles, while the permeability of composites was affected predominantly by inner demagnetizing fields due to the insulation. The numbers of moving domain walls involved in magnetization reversal were analyzed in connection with the magnetic properties.</p> </abstract>ARTICLE2022-04-13T00:00:00.000+00:00Sinter Hardening of Cr-Mo Pre-Alloyed Steels as a Function of the Carbon Content<abstract> <title style='display:none'>Abstract</title> <p>Sinter hardening is a technique that is frequently employed in powder metallurgy parts production since it is an economical, clean, and environmentally friendly procedure. Since the cooling rates are however significantly lower than e.g. in water or oil quenching, alloy systems have to be used that ensure martensite formation already at moderate cooling rates. In the present study, quenching dilatometry was used to investigate the hardenability of two types of Cr pre-alloyed steels, Fe-3Cr-0.5Mo and Fe-1.5Cr-0.2Mo, the carbon content being varied, and sinter hardening diagrams were plotted. It showed that this parameter has a pronounced influence on the hardenability of the 3 % Cr alloy; in particular in the range 0.3…0.4 % combined C. For the lower alloyed system, in contrast, even 0.52 % combined C was insufficient to ensure martensite formation at the cooling rates typical for industrial sinter hardening. Finally, impact test specimens were prepared by sinter hardening at cooling rates typical for industry, and hardness, as well as impact energy, were determined.</p> </abstract>ARTICLE2022-03-17T00:00:00.000+00:00Announcements Photoelectron Spectroscopy Study of Europium Niobate Thin Film Prepared by Chemical Solution Deposition<abstract> <title style='display:none'>Abstract</title> <p>Transparent europium niobate EuNbO<sub>4</sub> (ENO<sub>F</sub>) thin film (~100 nm) was prepared by sol-gel/spin-coating process on alumina substrates with PbZrO<sub>3</sub> (PZ) interlayer and annealing at 1000°C. The X-ray diffraction (XRD) analyses verified the formation of the monoclinic M-EuNbO<sub>4</sub> and tetragonal T-EuNb<sub>5</sub>O<sub>14</sub> phases in ENO precursor and ENO<sub>F</sub> film. The surface morphology of powder precursor and microstructure of film were investigated by SEM analyses. Surface chemistry was investigated by X-ray photoelectron spectroscopy (XPS). The XPS demonstrated two valence states of Eu (Eu<sup>3+</sup>/Eu<sup>2+</sup>) in powder precursor as nanophosphor for lighting and display technologies. Eu concentration (at. %) decreases from 10 % in the precursor to 2 % in the film considering the substrate contains C, Al, Si, Pb, and Zr elements (40 %) at Nb (6 %) and O (52 %). The single valence state of Eu<sup>3+</sup> was confirmed in ENO film designed for the application in environmental electrolytic thin-film devices.</p> </abstract>ARTICLE2022-03-17T00:00:00.000+00:00Evaluation of the Corrosion Resistance of WC-Co Coating on AZ91 Applied by Electro Spark Deposition<abstract> <title style='display:none'>Abstract</title> <p>In order to enhance the surface properties of a magnesium-based substrate, WC-Co coating was applied on AZ91 alloy by electro spark deposition (ESD), successfully for the first time. The optimum parameters of the ESD process were achieved, based on the corrosion behavior and calculated corrosion rate of the coated samples when 5kHz and 25 A were chosen. For evaluation of the corrosion performance of the achieved WC-Co layers, polarization, and electrochemical impedance spectroscopy tests were carried out in the 3.5 wt % Na<sub>3</sub>PO<sub>4</sub> solution at room temperature. Polarization results show that the corrosion rate (mpy) is in the optimum condition almost half of a bulk sample of uncoated AZ91. Field emission scanning electron microscopy (FE-SEM) was used to examine the surface morphology of applied coatings. These results show that at a lower current, the amount of deposited WC-Co was reduced. The maximum surface microhardness obtained was 193 HV0.2.</p> </abstract>ARTICLE2021-07-31T00:00:00.000+00:00The Effect of Plasma Pretreatment on the Morphology and Properties of Hitus Coatings<abstract> <title style='display:none'>Abstract</title> <p>WC coatings prepared by High Target Utilization Sputtering (HITUS), a relatively new technology, were deposited on three types of substrates. These were silicon (111), steel (100Cr6), and ceramic (WC-Co). The influence of RF plasma power pretreatment on final properties of WC coatings was investigated with two interlayer materials for bonding. The morphology, roughness, and mechanical properties of coatings were studied. The relation between plasma RF power and roughness was found. No significant change in mechanical properties was detected with change in plasma RF power. The dependence of nanohardness and scratch behavior on HITUS WC coatings was investigated.</p> </abstract>ARTICLE2021-07-31T00:00:00.000+00:00Temperature-Dependent Electrical Characteristics of Disc-Shaped Compacts Fabricated using Calcined Eggshell Nano Powder and Dry Cassava Starch<abstract> <title style='display:none'>Abstract</title> <p>Disc-shaped compacts were fabricated from two mix proportions of calcined eggshell nanopowder and dry cassava starch and then used as test samples. The electrical resistance (R), thermal sensitivity index (β) and electronic activation energy (E<sub>a</sub>) of the samples measured over a temperature range from 35 to 75<sup>o</sup>C were found to decrease non-linearly in values with increasing temperature. It was also observed that the results obtained (R = 3.691E6 Ω – 6.210E7 Ω, β = 3812K – 5316K and Ea = 0.33 eV – 0.46 eV) fulfill market requirements by comparing very well with the established values for NTC thermistors. Hence, from manufacturing viewpoint, recycling of chicken eggshell wastes and cassava effluents can avail electronic industry with promising and alternative materials for fabrication of temperature sensing / monitoring / control devices suitable for engineering applications. This will also help to reduce environmental pollution.</p> </abstract>ARTICLE2021-07-31T00:00:00.000+00:00Finishing of Tubes using Bonded Magnetic Abrasive Powder in an Abrasive Medium<abstract> <title style='display:none'>Abstract</title> <p>Magnetic abrasive flow finishing (MAFF) is an unconventional process capable of producing fine finishing with machining forces controlled by a magnetic field. This process can be utilized for hard to achieve inner surfaces through the activity of extrusion pressure, combined with abrasion activity of a magnetic abrasive powder (MAP) in a polymeric medium. MAP is the key component in securing systematic removal of material and a decent surface finish in MAFF. The research background disclosed various methods such as sintering, adhesive based, mechanical alloying, plasma based, chemical, etc. for the production of bonded MAP. This investigation proposes bonded MAP produced by mechanical alloying followed by heat treatment. The experiments have been conducted on aluminum tubes to investigate the influence of different parameters like magnetic field density, extrusion pressure and number of working cycles. The bonded magnetic abrasive powder used in MAFF is very effective to finish tubes’ inner surfaces and finishing is significantly improved after processing.</p> </abstract>ARTICLE2021-07-31T00:00:00.000+00:00Powder Metallurgy Manufacturing of Iron Aluminides with Different Aluminium Contents and Magnesium Addition by Reactive Hot Pressing<abstract> <title style='display:none'>Abstract</title> <p>In this work, iron aluminide materials, which are promising candidates for high temperature applications, are manufactured through reactive hot pressing of elemental powder mixes, facilitating a straightforward preparation of well-densified materials with a high degree of microstructural homogeneity. The impact of varying Al additions on reaction behavior, microstructural and compositional features of the resulting materials is evaluated. Furthermore, the effect of adding 1 wt. % Mg on reactivity and phase formation is illustrated. The results show that reactive hot pressing of elemental powders in the Fe-Al and Fe-Al-Mg systems at 1000 °C results in residual porosities well below 5 %. Magnesium addition significantly increased reactivity between constituents, leading to slightly improved densification without exhibiting potentially detrimental segregation phenomena. The processing approach presented in this work leads to material characteristics which are promising in the context of developing materials with favorable mechanical and tribological performance at elevated temperatures.</p> </abstract>ARTICLE2021-07-31T00:00:00.000+00:00Calcium Phosphate Cement Modified with Silicon Nitride/Tricalcium Phosphate Microgranules<abstract> <title style='display:none'>Abstract</title> <p>Tetracalcium phosphate/monetite biocement was modified with 10 and 30 wt. % addition of highly porous silicon nitride/α-tricalcium phosphate (αTCP) microgranules with various content of αTCP. A composite cement powder mixture was prepared using mechanical homogenization of basic components. The accelerated release of dexamethasone from composite cement was revealed, which indicates their possible utilization for controlled drug release. The wet compressive strength of cements (&lt;17 MPa) was significantly reduced (more than 30%) in comparison with the unmodified cement and both compressive strength and setting time were influenced by the content of αTCP in microgranules. The addition of microgranules caused a 20% decrease in final cement density. Microgranules with a higher fraction of αTCP showed good in vitro SBF bioactivity with precipitation of hydroxyapatite particles. Microstructure analysis of fractured cements demonstrated excellent interconnection between microgranules and cement calcium phosphate matrix, but also showed lower mechanical strength of microgranule cores.</p> </abstract>ARTICLE2021-07-31T00:00:00.000+00:00Powder Metallurgy Progress, an international open-access journal with 20 years of publishing history the Extension of the Journal`s Scope Dependence of the Mechanical Properties on the Microstructural Parameters of WC-Co<abstract> <title style='display:none'>Abstract</title> <p>The effect of binder content and WC grain size on the mechanical properties is widely investigated in literature. An increase in binder amount and WC grain size leads to a decrease in hardness and an increase in fracture toughness. Actually, these correlations are related to the influence of binder content and WC grain size through the contiguity and mean binder free path, which are the microstructural parameters that affect the mechanical properties. The aim of this study is to verify the dependence of the two microstructural parameters that govern the WCCo mechanical behaviour, namely the contiguity and mean binder free path, on the mechanical properties of an extended range of WC-Co samples, which differ in terms of Co content and tungsten carbide grain size.</p> </abstract>ARTICLE2020-06-15T00:00:00.000+00:00Die Wall - Vs. Bulk Lubrication in Warm Die Compaction: Density, Microstructure and Mechanical Properties of Three Low Alloyed Steels<abstract> <title style='display:none'>Abstract</title> <p>The influence of die wall lubrication during warm die compaction on densification, microstructure and mechanical properties of three low alloy ferrous powders was investigated. Specimens were sintered at 1250°C. Die wall lubrication leads to higher green and sintered density and enhances the dimensional stability. It does not affect the microstructure of the matrix, while pores are smaller and more rounded than in bulk lubricated specimens. In TRS tests, both strength and deformation are higher in die wall lubricated specimens than bulk lubricated ones.</p> </abstract>ARTICLE2020-06-15T00:00:00.000+00:00Study on Sintering of Artificially Oxidized Steel Compacts<abstract> <title style='display:none'>Abstract</title> <p>Sintering of Cr-prealloyed PM steels requires atmospheres with good quality – low oxygen potential – to achieve satisfactory sintering results. But during heating even the best atmospheres may be oxidizing, the system turns to reducing conditions only at high temperatures, which can be monitored by thermal analysis. During the dewaxing process, oxidizing conditions are favourable for effective dewaxing without sooting and blistering. However, this may result in some oxygen pickup during heating, and then the final properties of the produced parts may be strongly influenced by this intermediate oxidation. This study demonstrates the behaviour of artificially oxidized steels (Fe-C and Fe3Cr-0.5Mo-C) during the sintering process by stepwise sintering. Iron and steel powder were slightly oxidized and then pressed and sintered at different temperatures. In parallel, as a second approach, pressed samples were oxidized and then sintered. Density, hardness and impact energy were measured and dilatometry/MS was used for online monitoring of the sintering process. The starting oxygen content of 0.20 to 0.30 wt% is high enough to change the sintering behaviour of the materials, but still leads to rather good properties. Thermal analysis showed that most of the oxygen picked up was present as iron oxides on the surface which were reduced by hydrogen at rather low temperatures, confirming that these were iron oxides, which also holds for the Cr-prealloyed variant. The biggest influence on the final performance was exerted by the final carbon content and the microstructural development of the material.</p> </abstract>ARTICLE2020-06-15T00:00:00.000+00:00Polymorphs of Neodymium Niobate and Tantalate Thin Films Prepared by Sol-Gel Method<abstract> <title style='display:none'>Abstract</title> <p>Neodymium niobate NdNbO4 (NNO) and tantalate NdTaO4 (NTO) thin films (~100 nm) were prepared by sol-gel/spin-coating process on Pb(Zr0.52Ti0.48)O3/Al2O3 substrates with annealing at 1000°C. The precursors of films were synthesized using Nb or Ta tartrate complexes. The XRD results of NNO and NTO films confirmed tetragonal T-NdNbO4 and T-NdTaO4 phases, respectively, with traces of monoclinic MNdNbO4 and M´-NdTaO4. The surface morphology and topography were investigated by SEM and AFM analysis. NTO was smoother with roughness 5.24 nm in comparison with NNO (6.95 nm). In the microstructure of NNO, small spherical (~ 20-50 nm) T-NdNbO4 and larger needle-like particles (~100 nm) of M-NdNbO4 phase were observed. The compact clusters composed of fine spherical T-NdTaO4 particles (~ 50 nm) and cuboidal M´-NdTaO4 particles (~ 100 nm) were found in NTO. The results of this work can contribute to formation of different polymorphs of films for the application in environmental electrolytic thin film devices.</p> </abstract>ARTICLE2020-06-15T00:00:00.000+00:00Influence of Sodium Alginate on Properties of Tetracalcium Phosphate/Nanomonetite Biocement<abstract> <title style='display:none'>Abstract</title> <p>The tetracalcium phosphate/nanomonetite (TTCPMH) biocements with the addition of sodium alginate were prepared by mechanical homogenization of powder mixture with hardening liquid containing sodium alginate. The effect of various viscosity of different alginates on properties of TTCPMH cement mixture was investigated. The medium viscous (MED) alginate had a more negative effect on setting process and compressive strength than low viscous (LOW) alginate. An approx. 50% decrease in mechanical properties (compressive strengths, Young´s modulus, work of fracture (WOF)) was revealed after an addition of 0.25 wt % with rapid fall above 1 wt % of LOW alginate in biocement. A statistically significant difference in the WOF was found between of 0.25 and 0.5 LOW alginate biocements (p&lt;0.035) whereas no statistical differences were revealed between WOF of 0.5 and 1 LOW alginate biocements (p˃0.357). In the microstructure of composite cements, the increased amounts of granular or finer needle-like nanohydroxyapatite particles arranged into the form of more separated spherical agglomerates were observed. A low cytotoxicity of cement extracts based on measurement of cell proliferation was revealed.</p> </abstract>ARTICLE2020-06-15T00:00:00.000+00:00Experimental Investigations on Impact Toughness and Shear Strength of Novel Lead Free Solder Alloy Sn-1Cu-1Ni-XAg<abstract><title style='display:none'>Abstract</title><p>Lead is known to be banned in alloy making, highlighting toxicity concerns and environmental legislations. Researchers and scholars around the globe were in immediate search of new lead free solder alloys which could potentially replace the old Sn-Pb alloy. In this comprehensive study, shear strength and impact toughness tests were conducted on Sn-1Cu-1Ni when different amounts of Ag (0.25, 0.5, 0.75 1 % by wt.) is added. Shear strength test is tested using micro force test system. Impact toughness test is analyzed using Charpy impact test set up by calculating the energy difference before and after impact. The study reveals that, Ultimate shear stress increased from 19 MPa to 21.3 MPa. Yield strength increased from 27.4 MPa to 29.7 Mpa. Impact toughness of the alloys increased from 9.4 J to 10.1 J. Thus, Sn-1Cu-1Ni-1Ag is found to have improved shear strength and impact toughness than Sn-1Cu-1Ni.</p></abstract>ARTICLE2020-06-15T00:00:00.000+00:00en-us-1