X-ray diffraction analysis of a sintered product made of electroerosive chromium-containing powder

This article presents the results of x-ray diffraction analysis of a sintered sample made of X13 alloy electroerosive materials obtained in butyl alcohol. It was found that in the sintered sample by the method of spark plasma sintering from alloy X13, the main phases are Fe, Cr, and FeNi3.

The Impact of Preparation Techniques on the Properties of Magnesium Aluminate Spinel

In this work, two different methods namely; dry mixing and ball milling followed by the cold isostatic press were employed to synthesize Magnesium aluminate spinel (MgAl2O4). The phase diffraction and morphological characteristic of the sintered product were analyzed using X-Ray diffraction (XRD), Scanning Electron Microscopy (SEM). The Archimedes principle for determining viscosity and porosity of MgAl2O4. The main aim of this study to compare preparation techniques on the properties of the final spinel product. The results show that the ball milling method has an advantage over the dry mixing technique. In this technique, bigger crystals, well-compacted grains, higher density, and lesser reduction size and porosity were observed. an increase in the period of milling process was found to improve all these characteristics of MgAl2O4 spinel.

Processing Optimization for Metal Injection Molding of Orthodontic Braces Considering Powder Concentration Distribution of Feedstock

Metal injection molding (MIM) utilizes a compound consisting of metal powder particles and a binding agent as the feedstock material. The present study combines MIM mold flow simulations with the Taguchi method to clarify the individual and combined effects of the main MIM process parameters on the metal powder concentration distribution in the final sintered product. The results show that the molding process should be performed using a short filling time, a high melt temperature, a low packing pressure, a low mold temperature, and a small gate size. Given these process settings, the powder concentration uniformity and phase separation effect are significantly improved; giving rise to a better aesthetic appearance of the final sintered product and an enhanced mechanical strength.

Nanoscale Analysis on Spark Plasma Sintered Fly-Ash Bricks and their Comparative Study with SiN-Zr Refractory Bricks

Background: Industries such as thermal power plants use coal as a source of energy and release the combustion products into the environment. The generation of these wastes is inevitable and thus needed to be reused. In India, coals with high ash content usually between 25 to 45% are used. The refractory bricks that were used earlier in steel industries were mainly based on silica, magnesia, chrome, graphite. In modern days, several other materials were introduced for the manufacturing of refractory bricks such as mullite, chrome-magnesite, zircon, fused cast, and corundum. The materials selection for refractory brick manufacturing depends on various factors such as the type of furnace and working conditions. Objectives: The current work aims to focus on the fly-ash subjected to spark plasma sintering process with a maximum temperature of 1500 °C and pressure 60 MPa for 15 minutes and to characterize to observe the properties with respect to their microstructure. Methods: Fly-ash collected from Rourkela Steel Plant was sintered using spark plasma sintering machine at the Indian Institute of Technology, Kharagpur. The powder placed in a die was subjected to a heating rate of 600-630 K/min, up to a maximum temperature of 1500˚C. The process took 15 minutes to complete. During the process, the pressure applied was ranging between 50 to 60 Mpa. 5-10 Volts DC supply was given to the machine with a pulse frequency of 30-40 KHz. The sintered product was then hammered out of the die and the small pieces of the sintered product were polished for better characterization. The bricks collected from Hindalco Industries were also hammered into pieces and polished for characterization and comparison. Results: The particles of fly-ash as observed in SEM analysis were spherical in shape with few irregularly shaped particles. The sintered fly-ash sample revealed grey and white coloured patches distributed around a black background. These were identified to be the intermetallic compounds that were formed due to the dissociation of compounds present in fly-ash. High- temperature microscopy analysis of the sintered sample revealed the initial deformation temperature (IDT) of the fly-ash brick and the refractory brick which were found to be 1298 °C and 1543 °C, respectively. The maximum hardness value observed for the sintered fly-ash sample was 450 Hv (4.413 GPa) which is due to the formation of nano-grains as given in the microstructure. The reason behind such poor hardness value might be the absence of any binder. For the refractory brick, the maximum hardness observed was 3400 Hv (33.34 GPa). Wear depth for the sintered fly-ash was found to be 451 μm whereas for the refractory brick sample it was 18 μm. Conclusion: The fly-ash powder subjected to spark plasma sintering resulted in the breaking up of cenospheres present in the fly ash due to the formation of intermetallic compounds, such as Cristobalite, syn (SiO2), Aluminium Titanium (Al2Ti), Magnesium Silicon (Mg2Si), Maghemite (Fe2O3), Chromium Titanium (Cr2Ti) and Magnesium Titanium (Mg2Ti), which were responsible for the hardness achieved in the sample. A large difference in the maximum hardness values of sintered fly-ash and refractory brick was observed due to the hard nitride phases present in the refractory brick.

ANALYSIS OF CHARACTERISTICS OF WEAR RESISTANCE OF SINTERED ITEMS FROM ELECTROEROSION LEAD BRONZE OBTAINED IN KEROSIN LIGHT

The article presents the results of a study of the wear resistance of sintered samples of lead erosion bronze. Dispersed particles were obtained by electroerosive dispersion of BrS30 alloy waste in a carbon-containing medium - illuminating kerosene. Then, the obtained erosion materials were pressed using a Herzog TP 20 hand-held table press at a pressure of 1500 MPa and sintered in a Nabertherm GmbH RS 80/300/13 furnace for 2 hours at a temperature of 827 ° C in argon atmosphere. Then studied the surface roughness of the obtained samples, the friction coefficient and the wear factor of the samples. The friction coefficient and the wear rate of the surface of the samples and the counterbody were measured on an automated friction machine according to the standard ball-disk test scheme. The tests were carried out in air at a load of 2 N and a linear speed of 10 cm / sec, a radius of curvature of wear of 5-6 mm, the friction path was 200 meters. It was shown that the roughness by three measurements of the sample surface is Ra = 0.38 μm, the height of the profile irregularities at 10 points 𝑅𝑧 = 10.3. The arithmetic mean deviation of the profile of the sintered product corresponds to the 8th class of roughness of the parts. The height of the profile irregularities at 10 points corresponds to the 6th class of roughness of the parts. The friction coefficient was 0.395. The wear factor of the sample was 347x10 mm3Nm.

Fabrication of Copper Foam Plate Using Friction Sintering

A novel friction sintering process is used to obtain large copper foam plates using sintering and dissolution process. The process ensures easy and quick removal of the sintered product. Heat and pressure generated by downfeed of rotating tungsten tool pressed against a “top plate” results in solid-state sintering of copper powder particles. The large sized sintered part was obtained by providing a scan path for tool covering the “die” containing Cu-NaCl mixture. Note that no pre-compression of Cu-NaCl is done before the start of the process. Compaction and sintering both happen during the course of friction sintering. Scanning electron microscopy (SEM) images of fracture surface indicate that pore morphology is dictated by the morphology of NaCl particles. Temperature increases with the increase in plunge depth. The stress-strain curves for obtained foam in compression are similar to the reported in.

Analysis of the initial-stage sintering of mechanically activated SrTiO3

The initial-stage of sintering plays a significant role in determining the final microstructure that defines the main characteristics of electroceramics materials such as functional properties. In this article non-isothermal sintering of non-activated and mechanically activated SrTiO3 samples was investigated up to 1300?C. Dilatometric curves indicate that mechanical activation leads to an earlier onset of sintering, suggesting that it should lead to a more homogenous and denser sintered product. Analysis of the initial stage of sintering reveals that the sintering process of all examinated samples consists of tw? or three overlapping single-step processes, with a change in the dominant mass transport mechanism. The values of apparent activation energy of the considered single-step process exhibit a significant decrease with an increase in mechanical activation time. The values of the density of samples after isothermal sintering indicate that the final stage of sintering has not been reached by 1300?C.

Ti2AlC/TiAl Matrix Intermetallic Compound Prepared by In Situ Hot Pressing

As the new structural material, TiAl intermetallic compound has great potential application in aerospace engine, energy and automotive fields. But the bottleneck problems including poor room temperature ductility and high-temperature oxidation resistance limit its application. Ti2AlC possesses an unusual combination of the merits of both metals and ceramics, which is considered the best reinforcement for TiAl intermetallic compound. In the present work, Ti2AlC/TiAl matrix intermetallic compound was successfully fabricated by in situ hot pressing method from the mixture of Ti/Al/TiC. The phase transitions were investigated by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The microstructure of the product was studied by scanning electron microscopy (SEM). Ti reacted with Al liquids to form Ti-Al intermetallics below 900 °C firstly. With increasing temperature (above 900 °C), a part of TiAl intermetallics reacted with TiC to form Ti2AlC reinforcement. The as-sintered product presented dense and typical lamellar structure. The in-situ synthesized fine Ti2AlC contributed to improve the strength of TiAl matrix intermetallic compound.

Synthesis of AlN-SiC Ceramics by Hot Pressing

AlN-SiC ceramics were prepared at 1950°C by hot pressing (HP) of AlN/SiC powders in stoichiometric proportion. The sintered product was characterized using X-ray diffraction (XRD). Scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS) were utilized to investigate the morphology characteristics. The results show that AlN-SiC phase is well-developed with a close and lamellar structure. The grains are plate-like with the size of 1-3μm, the thickness of 3-5μm and elongated dimension. The results showed that the products had the density of 99 percent of the theoretical, bending strength of 550-800 MPa and fracture toughness of 5-6 MPa·m1/2. The distribution of AlN-SiC grains is relatively uniform.