scholarly journals Fractography and Porosity Analysis of Cr and Cr-Mo PM Steels

2016 ◽  
Vol 61 (3) ◽  
pp. 1613-1622 ◽  
Author(s):  
P. Kulecki ◽  
E. Lichańska ◽  
A. Radziszewska ◽  
M. Sułowski
Keyword(s):  
Computer Software ◽  
Horizontal Tube ◽  
Graphite Powder ◽  
Alloyed Powder ◽  
Single Action ◽  
Sintered Steels ◽  
Ductile Fractures ◽  
Porosity Analysis ◽  
Carbon Concentrations ◽  
Horizontal Tube Furnace

AbstractThe aim of the study was to evaluate the effect of processing variables on the porosity and fractography of Cr and Cr-Mo PM steels. The measurements were performed on sintered steels made from commercial Höganäs pre-alloyed powders: Astaloy CrA, Astaloy CrL and Astaloy CrM with two different carbon concentrations (0.2% and 0.6%) added in the form of ultra fine graphite powder grade C-UF. Following mixing in Turbula mixer for 30 minutes, green compacts were single-action pressed at 660 MPa according to PN-EN ISO 2740 standard. Sintering was carried out in a laboratory horizontal tube furnace at 1120°C and 1250°C for 60 minutes, in an atmosphere containing 5%H2and 95%N2. After sintering, the samples were tempered at 200°C for 60 minutes in air. For porosity evaluation computer software was employed. Hitachi S-3500M SEM equipped with EDS (made by Noran) was employed for fracture analysis. The steel based on Astaloy CrM pre-alloyed powder is characterized by fine pores and good mechanical properties. When sintered at 1250°C, it had area of pores approx. 7.12 μm2, ultimate tensile strength (UTS) about 679 MPa and elongation about 4%. The steels were characterized by ductile/cleavage and ductile fractures.

scholarly journals The Effect of Processing Parameters on Microstructure and Mechanical Properties of Sintered Structural Steels Based on Prealloyed Powders / Wpływ Parametrów Wytwarzania Na Strukturę I Własności Mechaniczne Spiekanych Stali Wykonanych Na Bazie Proszków Stopowych

2015 ◽  
Vol 60 (4) ◽  
pp. 2543-2548 ◽  
Author(s):  
P. Kulecki ◽  
E. Lichańska ◽  
M. Sułowski
Keyword(s):  
Mechanical Properties ◽  
Mechanical Testing ◽  
Graphite Powder ◽  
Processing Parameters ◽  
Structural Steels ◽  
Alloyed Powder ◽  
Production Parameters ◽  
Sintered Steels ◽  
Alternative Material ◽  
Horizontal Furnace

The object of the study was to evaluate the effect of production parameters on the structure and mechanical properties of Cr and Cr-Mo PM steels. The measurements were performed on sintered steels made from commercial Höganäs pre-alloyed powders: Astaloy CrA, Astaloy CrL and Astaloy CrM mixed with carbon, added in the form of graphite powder grade C-UF.Following mixing in a Turbula mixer for 30 minutes, green compacts were single pressed at 660 MPa according to PNEN ISO 2740 standard. Sintering was carried out in a laboratory horizontal furnace at 1120°C and 1250°C for 60 minutes, in 5%H2-95%N2atmosphere. After sintering, the samples were tempered at 200°C for 60 minutes in air. The steels are characterized by ferritic - pearlitic, bainitic - ferritic and bainitic structures.Following mechanical testing, it can be assumed that steel based on Astaloy CrA pre-alloyed powder could be an alternative material for steels based on Astaloy CrL powder. These steels sintered at 1250°C with 0.6% C had tensile strengths about 650 MPa, offset yield strengths about 300 MPa, elongations about 8.50 %, TRSs about 1100 MPa, hardnesses 220 HV.

scholarly journals Feasibility of nickel extraction from Indian chromite overburden by solid state reduction and smelting route

2020 ◽  
Vol 56 (2) ◽  
pp. 229-235
Author(s):  
P. Ganesh ◽  
Dishwar Kumar ◽  
S. Agrawal ◽  
Mandal Kumar ◽  
N. Sahu ◽  
...  
Keyword(s):  
Solid State ◽  
Horizontal Tube ◽  
Low Grade ◽  
State Reduction ◽  
Nickel Extraction ◽  
Reducing Atmosphere ◽  
Chromite Overburden ◽  
Solid State Reduction ◽  
Horizontal Tube Furnace ◽  
Direct Smelting

The present work demonstrates the extraction of nickel from low-grade chromite overburden by using solid state reduction and direct smelting route. Goethite & Quartz are present as major phases whereas chromite, hematite were identified as minor phases in the mineral. Solid state reduction of pellets were carried out inside a horizontal tube furnace at 1000?C, 1200?C, 1400?C for 30, 60, 90 and 120 minutes respectively with creating reducing atmosphere. Pellets of varying basicity (i.e. 0.5, 0.6, 0.7, 0.8 and 0.9) were used directly in the EAF for smelting studies. Highest percent of nickel (2%) having ~ 91% recovery were obtained in solid state reduction route for pellets which was reduced at 1400?C for 120 minute. Similar recovery (~90%) of nickel was obtained inside the ingot (0.67% Ni ) by using pellets of 0.9 basicity through smelting route. From the present investigation, it could be concluded that the solid state reduction as well as smelting routes are feasible for the recovery of nickel from low grade chromite overburden. The production of nickel pig (low grade ferronickel) could also be feasible by smelting route.

scholarly journals Single-Crystalline Metal Oxide Nanostructures Synthesized by Plasma-Enhanced Thermal Oxidation

Nanomaterials ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1405 ◽  
Author(s):  
Guo ◽  
Košiček ◽  
Fu ◽  
Qu ◽  
Lin ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Horizontal Tube ◽  
Single Crystalline ◽  
Oxide Nanostructures ◽  
Plasma Species ◽  
Custom Made ◽  
Metal Oxide Nanostructures ◽  
Metal Oxide Nanomaterials ◽  
Crystalline Metal ◽  
Horizontal Tube Furnace

To unravel the influence of the temperature and plasma species on the growth of single-crystalline metal oxide nanostructures, zinc, iron, and copper foils were used as substrates for the study of nanostructure synthesis in the glow discharge of the mixture of oxygen and argon gases by a custom-made plasma-enhanced horizontal tube furnace deposition system. The morphology and microstructure of the resulting metal oxide nanomaterials were controlled by changing the reaction temperature from 300 to 600 °C. Experimentally, we confirmed that single-crystalline zinc oxide, copper oxide, and iron oxide nanostructures with tunable morphologies (including nanowires, nanobelts, etc.) can be successfully synthesized via such procedure. A plausible growth mechanism for the synthesis of metal oxide nanostructures under the plasma-based process is proposed and supported by the nanostructure growth modelling. The results of this work are generic, confirmed on three different types of materials, and can be applied for the synthesis of a broader range of metal oxide nanostructures.

Effect of Shot Peening on the Fatigue Behavior of some Sintered Steels

2011 ◽  
Vol 488-489 ◽  
pp. 511-514
Author(s):  
Sergio Baragetti ◽  
Riccardo Gerosa ◽  
Giuseppe Silva ◽  
Barbara Rivolta
Keyword(s):  
Shot Peening ◽  
Mechanical Treatment ◽  
Fatigue Behavior ◽  
Alloyed Powder ◽  
Local Surface ◽  
Surface Layers ◽  
Bending Tests ◽  
Surface Densification ◽  
Sintered Steels ◽  
Surface Residual Stresses

Shot peening is a mechanical treatment usually performed on metals for improving the mechanical properties of the surface layers. The application of such treatment to sintered steels causes a local surface densification and the birth of residual compression stresses. In this paper, the effect of different shot peening cycles, selected after a preliminary optimization, has been investigated focusing especially on the fatigue resistance measured by bending tests and on the surface residual stresses measured by XRD technique. Two high performances PM steels were considered: the former was sintered starting from a diffusion bonded powder, whereas the latter is based on a pre-alloyed powder. Two different nominal densities were considered, 6.9g/cm3 and 7.1g/cm3.

Effect of Silica Sources on Synthesis of Alumina-Mullite-Silicon Carbide Composite

2012 ◽  
Vol 488-489 ◽  
pp. 607-611 ◽  
Author(s):  
Sutham Niyomwas
Keyword(s):  
Silicon Carbide ◽  
Carbothermal Reduction ◽  
Rice Husk Ash ◽  
Horizontal Tube ◽  
Argon Gas ◽  
Carbide Composite ◽  
Whisker Morphology ◽  
Horizontal Tube Furnace ◽  
Sem Analyses

Synthesis of alumina-mullite-silicon carbide composite (Al2O3-Al6Si2O13-SiCw) was obtained in situ by carbothermal reduction of a mixture of kaolin and two different silica sources. The carbothermal reduction was carried out in a horizontal tube furnace under flow of argon gas. The synthesized products were mixtures of alumina, mullite and silicon carbide in the form of whiskers. The effects of adding two different silica sources of rice husk ash and silica powder to the mixture of kaolin and activated carbon were investigated. XRD and SEM analyses indicate complete reaction of precursors to yield Al2O3-Al6Si2O13-SiC as product powders, with the SiC having whisker morphology.

Synthesis of AlN Nanowires and Characterization with Properties of Composite Materials

2012 ◽  
Vol 583 ◽  
pp. 18-21
Author(s):  
Long Hai Shen ◽  
Nan Wang
Keyword(s):  
Horizontal Tube ◽  
Hexagonal Wurtzite Structure ◽  
Average Diameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electron Microscopies ◽  
Structure And Morphology ◽  
Vapor Liquid Solid Mechanism ◽  
Source Materials ◽  
Horizontal Tube Furnace

The experiments were carried out in a horizontal tube furnace using Al and NH3 as the source materials. The structure and morphology of the as-synthesized AlN nanowires are characterized by X-ray diffraction, scanning electron microscopies and Raman spectrum. The results indicated that the structure of synthesized AlN nanowire is hexagonal wurtzite structure, the length of the AlN nanowire is between several micrometers and the the average diameter is about 100 nm.The growth of the AlN nanowires can be expelained by vapor–liquid-solid mechanism.

Direct growth of graphene nanowalls on quartz substrates as transparent conductive electrodes for perovskite solar cells

2018 ◽  
Vol 11 (01) ◽  
pp. 1850009 ◽  
Author(s):  
Guanhua Lin ◽  
Yaqing Zhou ◽  
Yu Wang ◽  
Xin Yan ◽  
Baoshan Wu ◽  
...  
Keyword(s):  
Solar Cells ◽  
Perovskite Solar Cells ◽  
Three Dimensional ◽  
Horizontal Tube ◽  
Growth Time ◽  
Frequency Plasma ◽  
Direct Growth ◽  
Quartz Substrates ◽  
Transparent Conductive Electrodes ◽  
Horizontal Tube Furnace

An effective method to directly produce high-quality graphene nanowalls (GNWs) on quartz substrates was demonstrated using an advanced self-assembled ratio-frequency plasma-enhanced horizontal tube furnace deposition system under different growth times from 60[Formula: see text]s to 150[Formula: see text]s at a substrate temperature of 850[Formula: see text]C without using any catalyst. The synthesized well-connected three-dimensional GNWs feature outstanding electrical and optical performance: the sheet resistance varies from 1053 [Formula: see text]/[Formula: see text] to 342 [Formula: see text]/[Formula: see text], while the corresponding transmittance ranges from 90.4% to 67.8% at a wavelength of 550[Formula: see text]nm under different growth times. We have also demonstrated that GNWs can be used as transparent conductive electrodes for perovskite solar cells. The highest photovoltaic conversion efficiency of 6.93% can be obtained for the GNWs deposited at a growth time of 120[Formula: see text]s. Hence, our study paves a new way of using GNWs as transparent conductive electrodes in perovskite solar cells.

Production of Metallic Iron from Iron Oxide (Fe2O3) Using End-of-Life Rubber Tyre and its Blends with Metallurgical Coke as Reductants

2013 ◽  
Vol 10 ◽  
pp. 1-12
Author(s):  
James Ransford Dankwah ◽  
Pramod Koshy
Keyword(s):  
Iron Oxide ◽  
End Of Life ◽  
High Purity ◽  
Metallic Iron ◽  
Horizontal Tube ◽  
Metallurgical Coke ◽  
Argon Gas ◽  
Composite Pellets ◽  
Infrared Gas Analyser ◽  
Horizontal Tube Furnace

The production of metallic iron from iron oxide using end-of-life tyres (RT) and its blends with metallurgical coke as reductants has been investigated through experiments conducted in a laboratory scale horizontal tube furnace. Composite pellets of iron oxide (96.89 % Fe2O3) with RT, coke and coke/RT blends (in four different proportions) were rapidly heated at 1500 °C under high purity argon gas and the off gas was continuously analysed for CO and CO2 using an online infrared gas analyser (IR). The extent of reduction after ten minutes, level of carburisation of the reduced metal and the total amount of CO2 emissions were determined for each carbonaceous reductant. The results indicate that metallic iron can be effectively produced from Fe2O3 using RT and its blends with coke as reductant. The extent of reduction and level of carburisation are significantly improved when coke is blended with RT. Blending of coke with RT resulted in significant decrease in CO2 emissions.

Effect of HDPE addition on the Pre-reduction of Mn3O4 to MnO by Metallurgical Coke

2014 ◽  
Vol 33 (4) ◽  
pp. 345-353 ◽  
Author(s):  
J.R. Dankwah ◽  
P. Koshy
Keyword(s):  
Mass Balance ◽  
High Density Polyethylene ◽  
Horizontal Tube ◽  
Gas Analysis ◽  
High Density ◽  
Metallurgical Coke ◽  
Argon Gas ◽  
Pure Argon ◽  
Composite Pellets ◽  
Horizontal Tube Furnace

AbstractThe effect of high density polyethylene (HDPE) addition on the pre-reduction of Mn3O4 to MnO by metallurgical coke (Coke) has been investigated through experiments conducted in a laboratory horizontal tube furnace coupled with off-gas analysis through an infrared (IR) gas analyser. Composite pellets of Mn3O4 with Coke, HDPE and blends of Coke with HDPE (in three different proportions) were rapidly heated at 1150 °C under pure argon gas and the off gas was analysed continuously for CO, CO2 and CH4. The extent of pre-reduction of Mn3O4 to MnO was then calculated by mass balance for removable oxygen. The results showed improvements in the extent of pre-reduction of Mn3O4 to MnO when coke is blended with HDPE. The time for complete pre-reduction was found to decrease with an increase in the amount of HDPE that was blended with coke. A decrease in CO2 emissions was observed with HDPE addition.

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