Science of Sintering

Issue 1 cover

2024-02-26T20:08:46+01:00

The Effect of Molten Salt on The Mechanical Properties and Microstructure of CuNiSi Alloys with Reinforced Fe

2024-02-26T20:08:47+01:00

In this study, CuNiSi alloys were produced using powder metallurgy in molten salt (KBr). In the Cu, Ni, and Si powder mixture, Fe was added at a rate of 2.5%, 5 and 7.5% and mechanical alloying was carried out for 4 hours at 400 rpm. Prepared powder mixtures were cold pressed under 600 MPa pressure and sintered for 3 hours at 900 ℃ in an argon atmosphere. Phase formation, microstructure, microhardness, electrical conductivity, and corrosion of the produced samples were analyzed in detail. Scanning electron microscope (SEM) was used to detect the changes in the microstructure of the produced samples, and an X-ray diffractogram (XRD) was used to determine the phases formed in the internal structure of the materials. In order to determine the mechanical properties of the produced samples, hardness analyzes were made with a microhardness measuring device. The electrical conductivity properties of the produced CuNiSi and CuNiSiFe alloys were determined due to the increase in the Fe ratio. Corrosion tests of the produced samples were determined by potentiodynamic polarization curves in a 3.5% NaCl solution. Fe-reinforced CuNiSi composite materials have been successfully produced in molten salt (KBr). CuNiSi alloy, the microstructure is dominated by the typical large and small particles. Fe element is homogeneously dispersed in the CuNiSi alloy instead of being separated using the Ni element. Fe particles have decreased the hardness of produced alloys. The electrical conductivity properties changed with increasing voltages depending on the increase of Fe supplementation, and as a result, the sample containing 7.5% Fe had the best electrical conductivity values. Results showed that by increasing the amount of Fe, the mechanical properties and corrosion resistance increased.

Influence of rare earth oxide and graphite on the mechanical and tribological properties of Fe/Cu based sintered friction materials

2024-02-26T20:08:58+01:00

Fe/Cu-based sintered friction materials are proven potential materials for heavy-duty applications. The current research explores the influence of rare earth oxide (Nd2O3) and graphite on the tribological characteristics of Fe/Cu-based friction materials. The constituents present in the friction material are Fe, Cu, Cg (1%, 3%, 5%, 7%), BaSO4, and Nd2O3 (5%). Optical microscopy and elemental mapping studies reveal the homogeneous distribution of elements in the matrix. Sintered density of the specimens showed a maximum of 70% of the theoretical density measured by Archimedes' principle. XRD analysis shows no new phase formation in all the sintered specimens. A peak microhardness result of 96 HV is obtained in specimen NG-01. The pin–on–disc tribotests are performed at an axial load of 50 N at a sliding velocity of 5.5 m/s. Specimen NG-03 with 3% graphite exhibited an optimum wear rate with a friction coefficient of 0.45. The surface morphology and elemental composition of the worn specimens are investigated. The morphological features inferred that the wear mechanism is predominantly mixed abrasive and adhesive.

Determination of the Effects of the Rebar-cement Bond Parameters Variation in UHPFRC using FA and ANN

2024-02-26T20:09:05+01:00

The experimental study included the design and production of ultra-high-performance steel fiber-reinforced concrete (UHPFRC). The physical and mechanical properties of UHPFRC were investigated in a laboratory setting. To investigate the properties of UHPFR concrete, three types of concrete and over 70 samples were used. Following that, samples were created to test the anchors' load-bearing performance. Six concrete slabs with a total of 108 pre-installed anchor samples and six concrete slabs with 108 post-installed chemical anchor samples were created. The analysis of the test findings comprised all individual results as well as the definition of the relationship between the anchor's tensile load capacity and other parameters. To accurately determine the individual influence of the investigated factors as well as their combined impact, a factorial experiment, and artificial neural networks were used in addition to normal statistical numerical studies. It was determined that both approaches offer advantages. The results obtained show matches in certain parts. Due to the way data is processed in different ways, there are also significant differences between them.

The influence of printing orientation on the flexural strength of PA 12 specimens produced by SLS

2024-02-26T20:09:09+01:00

This article aims to investigate the mechanical characteristics of specimens fabricated using Selective Laser Sintering technology. The research covers flexural specimens, produced by PA12 materials. CAD model dimensions were selected according to the ISO 178 standard, and the chosen specimen geometry is 96 x 8 x 4 [mm] in bulk. All specimens were produced using a specialized machine Fuse 1 (FormLabs, Summerville, MA). Four specimen batches were produced, each with a different printing orientation (i.e. vertical and horizontal) and location on the printing plate (i.e. in the middle and on the edge of the powder bed). The specimens are tested using a Shimadzu universal machine for testing the mechanical characteristics of materials, AGS-X 100 kN, with a unique additional tool for testing 3-point bending specimens.

The effects of hot rolling process on mechanical properties, corrosion resistance, and microstructures of mo-ni alloyed steels produced by powder metallurgy

2024-02-26T20:09:15+01:00

This study examined the effects of hot rolling on the microstructure, tensile strength, and corrosion behaviors of three different alloy steels made by powder metallurgy: Fe-0.55C, Fe-0.55C3Mo, and Fe-0.55C-3Mo-10Ni. 700 MPa pressure was applied to press the particles. The cold pressed samples were sintered in a mixed-gas atmosphere (90% nitrogen, 10% hydrogen) at 5°C/min up to 1400°C for 2 hours. Then, the produced steels were hot rolled with a deformation rate of 80%. The microstructures show that deformed Mo and Mo-Ni steels have finer microstructures, better mechanical properties than undeformed Mo and Mo-Ni steels, and MoC, MoN, or MoC(N) was formed in the Mo-Ni steels. The highest mechanical properties were obtained in rolled steel samples containing Mo-Ni, followed by rolled Mo steel and rolled carbon steel samples, and then unrolled samples. Additionally, Tafel curve analysis demonstrated that alloy corrosion resistance rose as Ni concentration increased. It has also been observed that the hot rolling process improves corrosion resistance. The increase in the density value with the rolling process emerged as the best supporter of corrosion resistance.

Effect of Cr Limits on Microstructure and Mechanical Properties of P/M 316L Austenitic Steel

2024-02-26T20:09:21+01:00

This study investigated the effect of the Cr limits on the microstructure and mechanical properties of 316L alloy. Five 316L alloys with varying Cr contents (16.8, 17.1, 17.3, 17.8 and 18.8 wt.%) were produced by the powder metallurgy (P/M) method. Microstructure studies and phase analysis were performed with a scanning electron microscope (SEM), optical microscopy (OM), and energy dispersive spectrometry (EDS). Tensile tests and hardness measurements were performed to evaluate the hardness, strength, and ductility of the alloys. The results showed that Cr addition affected the porosity and grain size of the alloys, as well as the formation of precipitates. The ultimate tensile strength reached a maximum at 17.3 wt.% Cr and then decreased with further Cr addition. Ductility decreased with increasing Cr under the influence of precipitates formed and changes in microstructure. On the other hand, the hardness increased with increasing Cr inversely to the ductility.

Influence of sintering temperature on structure, physical, and optical properties of wollastonite based glass-ceramic derived from waste eggshells and waste soda-lime-silica glasses

2024-02-26T20:09:25+01:00

Calcium oxide from discarded eggshells and waste soda-lime-silica were utilized in this study to make wollastonite (CaSiO3) based glass-ceramics. The calcium oxide and silica were made using the melt-quenching process and sintered for 2 hours at 700 to 1000 °C. The XRD data verified that the wollastonite crystalline peak appeared at high sintering temperatures, with crystalline phase values of 39.74%, 47.37%, and 48.91% as the sintering temperature increased at 800-1000°C, respectively. Additionally, crystalline size and phase have no obvious change at 8001000°C, where the intensity has increased by the sintering temperature. The FTIR spectra revealed the wollastonite phase vibration at the wavelength of 501 cm-1, 650cm-1, 715cm-1, 808cm-1, 931cm1, 2129 cm-1. Additionally, the FTIR spectral confirm the Si-O-Ca vibration band at the wavelength of 650 cm1. For the optical sample, the value of indirect allowed transition with n=2 is the ideal value of the optical band gap based on a band gap rise from 3.89 to 4.23 eV with increasing sintering temperature. The value n=2 which is the indirect allowed transition is the optimal value of the optical band gap based on the value increase from 3.89-4.23 eV as the temperature increase. The synthesis approach introduced the low-cost method, recycle approach, simple and yet uses cheap starting materials for fabrication of wollastonite glass-ceramics product.

Cobalt supported chitosan-derived carbon-smectite catalyst in Oxone® induced dye degradation

2024-02-26T20:09:33+01:00

Catalytic degradation of tartrazine in the presence of Oxone® activated by a catalyst constituted of cobalt supported on a nanocomposite of smectite with chitosan-derived carbon was investigated. The catalyst was synthesized using cobalt impregnation followed by carbonization at 773 K in an inert atmosphere. The synthesized catalyst was previously fully characterized using appropriate characterization methods, including XRPD, XPS, FTIR, HR-TEM, and low-temperature N2-physisorption analysis. The catalytic experiments were performed by varying different experimental parameters (dye concentration, Oxone® concentration, temperature, and initial pH of the reaction solution). The kinetic and thermodynamic parameters were estimated from the experimental results. The kinetics data showed the best fit with the pseudo-first-order kinetics model. The activation energy of the investigated degradation process was calculated according to the Arrhenius equation. The catalyst showed excellent performance at low temperatures even at 298 K, and in the wide range of pH values.

The influence of strontium content and sintering temperature on monazite stability

2024-02-26T20:09:39+01:00

This paper shows a simple way to synthesize a series of Ce1-xSrxPO4 ceramic materials using acetate solutions of Ce and Sr instead of nitrate which were used so far. For synthesis, the preparation method was used by simple mixing of acetate solutions of Ceand Sr(, with NaH2PO4 at room temperature, and the studied compositions were Ce1-xSrxPO4 (where x = 0, 0.1, 0.2, 0.3, 0.4, 0.5). The disintegration of Sr in monazite structures in different sintering temperature ranges from 600 °C to 1000 °C was investigated. The X-ray diffraction was used to track the evolution of the phase composition with thermal treatment. The morphology of sintered ceramics was obtained by scanning electron microscopy and vibrational bands of selected spectra were observed using the FT-IR method. Relative geometric density of selected samples was evaluated. The most favorable conditions for obtaining high-temperature Ce, Sr phosphate-based ceramic material are reported.

Synthesis and Characterization of High-Entropy A2B2O7 Pyrochlore with Multiple Elements at A and B Sites

2024-02-26T20:09:44+01:00

Single nano high-entropy pyrochlore-type compound (A2B2O7) with 7 different rare-earth cations at site A and 3 different metal cations at site B with equiatomic amounts (7A1/7)2(3B1/3)2O7 is successfully obtained. The powder with nominal composition (La1/7Sm1/7Nd1/7Pr1/7Y1/7Gd1/7Yb1/7)2(Sn1/3Hf1/3Zr1/3)2O7 was fabricated by reacting metal nitrates (site A) and metal chlorides (site B) with glycine during the combustion reaction. The XRD analysis revealed that the powder attained during synthesis is in an amorphous state. To induce crystallization of the obtained pyrochlore structure, the post-calcination process at 600-1500 °C was conducted and studied. Results of this study showed that the monophase pyrochlore (A2B2O7) structure is obtained during the calcination at 900 °C. The high-density ceramic pellet with 97% of theoretical density and free of any additives was obtained through pressureless sintering at 1650 °C for 4 h in the air using the powder calcined at 900 °C.