scholarly journals Dilatometric investigations of Fe – Cr – Mo – C system

2018 ◽  
Vol 2 (2) ◽  
pp. 1-13
Author(s):  
Maciej Sulowski ◽  
Ewa Lichańska ◽  
Paweł Kulecki ◽  
Monika Tenerowicz-Żaba ◽  
Anna Staniek
Keyword(s):  
Carbon Content ◽  
Sintering Behavior ◽  
Density Level ◽  
Pressing Pressure ◽  
Pure Nitrogen ◽  
Sintering Atmosphere ◽  
Single Action ◽  
Dimensional Changes ◽  
Heating And Cooling ◽  
Final Density

Sintering behavior in high purity nitrogen and mixture of 5% H2-95% N2 of Fe-(Cr)-(Mo)-C system was investigated. The mixtures, differ from chromium, molybdenum and carbon content were prepared in Turbula mixer. Then, using single-action pressing in a rigid die at pressing pressure 400 MPa, green compacts with density level 5.9±0.17 g/cm3 were pressed. Sintering was carried out in a horizontal push rod dilatometer Netzsch 402E at 1120 and 1250°C for 60 min. Heating and cooling rates were 10 and 20°C/min., respectively. After heating, compacts were isothermal sintered at 1120 or 1250°C for 60 minutes an cooled up to 200°C, then isothermally hold for 60 minutes and definitely cooled to the room temperature. Pure nitrogen and mixture of 5% H2-95% N2 were employed as sintering atmospheres. During investigations the influence of isothermal sintering temperature, chemical composition of sintering atmosphere, chromium, molybdenum and carbon content was followed by dilatometry. The aim of investigations was to determine transformation temperatures. It was shown that the dimensional changes occurring during heating and isothermal sintering and the final density of sintered compacts are influenced by sintering parameters and the alloying elements concentration in powder mixture.

Atmosphere Effect on Sintering Behaviour of Astaloy CrM and Astaloy CrL Höganäs Powders with Manganese and Carbon Additions / Wpływ Atmosfery Na Spiekalność Komercyjnych Proszków Höganäs Astaloy CrM I Astaloy CrL Z Dodatkami Manganu I Węgla

2012 ◽  
Vol 57 (4) ◽  
pp. 1001-1009 ◽  
Author(s):  
T. Pieczonka ◽  
M. Sułowski ◽  
A. Ciaś
Keyword(s):  
Chemical Composition ◽  
Sintering Temperature ◽  
Minor Effect ◽  
Sintering Atmosphere ◽  
Dimensional Changes ◽  
Atmosphere Effect ◽  
Final Density ◽  
Sintering Behaviour ◽  
Carbon Additions ◽  
Dilatometric Data

Dilatometric data for Astaloy CrM (3% Cr-0.5% Mo) and Astaloy CrL (1.5% Cr-0.2% Mo) powders with additions of 0.3% carbon and 3.0% manganese during sintering cycles up to 1120 and 1250°C in different atmospheres are reported. For comparison, also Astaloy CrM and Astaloy CrL powders were investigated. Starting with green densities of approx. 6.8 g/cm3, the final density of sintered compacts was influenced mainly by the sintering temperature, while the results showed the only minor effect of the sintering atmosphere on the final dimensional changes. However, the sintering atmosphere influences the sintering behaviour, microstructure and the final chemical composition of sintered compacts. In sintered and in the dilatometer cooled Mn-Cr-Mo-C steels predominantly bainitic structures were obtained.

Sintering Behavior: Al–SiC Compacts in Different Atmospheres

2019 ◽  
Author(s):  
Tadeusz Pieczonka
Keyword(s):  
Fine Particles ◽  
Pure Aluminum ◽  
Sintering Behavior ◽  
Sintering Atmosphere ◽  
Dimensional Changes ◽  
Ceramic Bond ◽  
Large Particles ◽  
Solid Phases ◽  
Sic Reinforcement

The effect of sintering atmosphere on densification of Al–SiC compacts was investigated. Dimensional changes were monitored in situ in a dilatometer in flowing nitrogen, nitrogen/hydrogen mixture (95/5 by volume), and argon. Two grades of SiC powder were used—F240 characterized by large particles and FCN13 with very fine particles. Mixtures containing 10 and 30 vol.% of SiC reinforcement were prepared in a Turbula mixer. Green compacts of about 80% of theoretical density were made of each mixture. For comparison, compacts made of pure aluminum powder were also investigated. It was shown that nitrogen is the only sintering atmosphere producing shrinkage. This ceramic constituent lowers the sintering densification. Metallographic examinations of sintered composites revealed that sintering of compacts occurs in the presence of a liquid phase exclusively in nitrogen. The melt appearing in Al–SiC compacts is capable to wet the solid phases, which makes shrinkage possible and is beneficial for metal/ceramic bond formation.

Technological Aspects Concerning the Production Procedures of UO2-Gd2O3 Nuclear Fuel

2008 ◽  
Vol 591-593 ◽  
pp. 673-678 ◽  
Author(s):  
Michelangelo Durazzo ◽  
Humberto Gracher Riella
Keyword(s):  
Nuclear Fuel ◽  
Pore Formation ◽  
Kirkendall Effect ◽  
Experimental Results ◽  
Sintering Behavior ◽  
Negative Effects ◽  
The Poor ◽  
Final Density ◽  
Blending Method ◽  
Direct Incorporation

The direct incorporation of Gd2O3 powder into UO2 powder by dry mechanical blending is the most attractive process for producing UO2-Gd2O3 nuclear fuel. However, previous experimental results by our group indicated that pore formation due to the Kirkendall effect delays densification and, consequently, diminishes the final density of this type of nuclear fuel. Considering this mechanism as responsible for the poor sintering behavior of UO2-Gd2O3 fuel prepared by the mechanical blending method, it was possible to propose, discuss and, in certain cases, preliminarily test feasible adjustments in fabrication procedures that would minimize, or even totally compensate, the negative effects of pore formation due to the Kirkendall effect. This work presents these considerations.

The Influence of Process Parameters on Microstructure and Mechanical Properties of PM Al+4 wt. %Cu Alloy

2016 ◽  
Vol 682 ◽  
pp. 252-258
Author(s):  
Anna Tylek ◽  
Beata Leszczyńska-Madej ◽  
Albert Zygiert
Keyword(s):  
Process Parameters ◽  
Bending Strength ◽  
Compaction Pressure ◽  
Substantial Effect ◽  
Nitrogen Atmosphere ◽  
Point Of View ◽  
Pressing Pressure ◽  
Influence Of Process Parameters ◽  
Single Action ◽  
Three Point Bend Test

Attempts have been made to describe the influence of the process parameters, such as compaction pressure and sintering atmosphere on the microstructure and properties of PM Al4Cu alloy. Homogenous mixtures of Al4Cu elemental powders were achieved by tumbling powders for 30 minutes in the Turbula T2F mixer. The powders were subsequently cold compacted under pressures of: 200MPa, 300MPa and 400MPa in a rigid die on a single action press. The green compacts were sintered in two different atmosphere - nitrogen and vacuum at 600°C for one hour. After that, the samples sintered in nitrogen atmosphere were re-pressed and re-sintered (2p2s) under the same conditions. The green compact and as-sintered densities were measured using the geometric method. Additionally, the Brinell hardness and the bending strength in three point bend test were determined. The microstructure of the samples was also analyzed using both the light microscopy (LM) and scanning electron microscopy (SEM).The obtained results show, that optimal pressing pressure is 300MPa. Increasing pressure to 400 MPa has not a substantial effect on increase of the final sample density. Therefore applying higher compaction pressure (over 300MPa), from the economical point of view, is unnecessary.

Application of Master Sintering Curve Theory to Predict and Control the Sintering of Nanocrystalline TiO2 Ceramic

2008 ◽  
Vol 368-372 ◽  
pp. 1588-1590
Author(s):  
Da Li ◽  
Shaou Chen ◽  
Wei Quan Shao ◽  
Xiao Hui Ge ◽  
Yong Cheng Zhang ◽  
...  
Keyword(s):  
Sintering Behavior ◽  
Heating Rates ◽  
Temperature Function ◽  
Rutile Tio2 ◽  
Densification Curve ◽  
Final Density ◽  
Thermal Histories ◽  
Constant Heating ◽  
And Control ◽  
Temperature Time

Master sintering curve (MSC), in which the sintered density is a unique function of the integral of a temperature function over time, is insensitive to the heating path. In this paper, the densification of rutile TiO2 was continuously recorded at heating rates of 2 °C/min and 5 °C/min, respectively, by dilatometer. The MSC for rutile TiO2 was constructed for pressureless sintering using constant heating rate date based on the combined-stage sintering model. The construction and application of the MSC were described in detail for different thermal histories. The MSC can be used to predict and control the densification, final density, and microstructure evolution during the whole sintering. The final density can be predicted for an arbitrary temperature–time path. A good consistence exists between the predicted and experimental densification curve, confirming that it is possible to accurately predict and control the sintering behavior of TiO2 from the initial to final stage of sintering using MSC.

Nominally Equivalent Powders for P/M Steels: Analysis of Response to Sintering and Differences at Various C Content

2007 ◽  
Vol 534-536 ◽  
pp. 701-704 ◽  
Author(s):  
G.F. Bocchini ◽  
M.G. Ienco ◽  
M.R. Pinasco ◽  
E. Stagno ◽  
Andrea Baggioli ◽  
...  
Keyword(s):  
Statistical Approach ◽  
Raw Materials ◽  
Rupture Strength ◽  
Sintering Behavior ◽  
Industrial Equipment ◽  
Cost Difference ◽  
Dimensional Changes ◽  
Microhardness And Microstructure ◽  
Different Sources ◽  
Sintering Processes

Globalization enables P/M part makers to choose powders from different sources. Raw materials produced by a given process and having equal chemical composition are supposed to be equivalent. The differences in sintering behavior, in industrial equipment, have been investigated on P/M steels obtained from four diffusion-bonded powders (Fe + Ni + Cu + Mo) on atomized iron base, at the same alloy contents. Two levels of carbon and two sintering conditions have been investigated. Dimensional changes, C content, hardness, microhardness pattern, universal hardness, fractal analysis, pore features, microstructure features, and rupture strength have been compared, to characterize different raw materials. An index of homogeneity of microstructures, based on a specific statistical approach, does not agree completely with observed microstructures and pore feature. The results show that the claimed equivalence is not confirmed by experimental data. Analyses of microhardness and microstructure distributions seem powerful tools to rate the real equivalence of so claimed powders. P/M part makers may use the proposed approach to assess detectable differences on performances among powders that are declared as “true” substitute, so confirming or contradicting any even not negligible cost difference. The comparison methods here described and applied can also help powder producers to improve the suitability of their products to sintering processes.

Phase Stability and Sintering Behavior of 10mol%Sc2O3–1mol%CeO2–ZrO2 Ceramics

2009 ◽  
Vol 6 (2) ◽  
Author(s):  
Sergey Yarmolenko ◽  
Jag Sankar ◽  
Nicholas Bernier ◽  
Michael Klimov ◽  
Jay Kapat ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Room Temperature ◽  
Rhombohedral Phase ◽  
Impurity Level ◽  
Cubic Phase ◽  
Sintering Behavior ◽  
X Ray Diffraction ◽  
Chemical Route ◽  
Heating And Cooling ◽  
Secondary Ion

The phase composition and sintering behavior of two commercially available 10mol%Sc2O3–1mol%CeO2–ZrO2 ceramics produced by Daiichi Kigenso Kagaku Kogyo (DKKK) and Praxair have been studied. DKKK powders have been manufactured using a wet coprecipitation chemical route, and Praxair powders have been produced by spray pyrolysis. The morphology of the powders, as studied by scanning electron microscopy, has been very different. DKKK powders were presented as soft (∼100μm) spherical agglomerates containing 60–100nm crystalline particles, whereas the Praxair powders were presented as sintered platelet agglomerates, up to 30μm long and 3–4μm thick, which consisted of smaller 100–200nm crystalline particles. X-ray diffraction analysis has shown that both DKKK and Praxair powders contained a mixture of cubic (c) and rhombohedral (r) phases: 79% cubic +21% rhombohedral for DKKK powders and 88% cubic +12% rhombohedral for Praxair powders. Higher quantities of the Si impurity level have been detected in Praxair powder as compared to DKKK powder by secondary ion mass spectroscopy. The morphological features, along with differences in composition and the impurity level of both powders, resulted in significantly different sintering behaviors. The DKKK powders showed a more active sintering behavior than of Praxair powders, reaching 93–95% of theoretical density when sintered at 1300°C for 2h. Comparatively, the Praxair powders required high sintering temperatures at 1500–1600°C. However, even at such high sintering temperatures, a significant amount of porosity was observed. Both DKKK and Praxair ceramics sintered at 1300°C or above exist in a cubic phase at room temperature. However, if sintered at 1100°C and 1200°C, the DKKK ceramics exist in a rhombohedral phase at room temperature. The DKKK ceramics sintered at 1300°C or above exhibit cubic to rhombohedral and back to cubic phase transitions upon heating at a 300–500°C temperature range, while Praxair ceramics exist in a pure cubic phase upon heating from room temperature to 900°C. However, if heated rather fast, the cubic to rhombohedral phase transformation could be avoided. Thus it is not expected that the observed phase transitions play a significant role in developing transformation stresses in ScCeZrO2 electrolyte upon heating and cooling down from the operation temperatures.

Sintering of MoSi2

1993 ◽  
Vol 322 ◽  
Author(s):  
J.J. Petrovic ◽  
J.S. Idasetima
Keyword(s):  
Sintered Density ◽  
Sintering Temperature ◽  
Low Cost ◽  
Argon Atmosphere ◽  
Fabrication Process ◽  
Sintering Behavior ◽  
Sintering Atmosphere ◽  
Fundamental Nature ◽  
Sintering Time ◽  
Cold Pressed

AbstractDespite the fundamental nature of sintering and its importance as a low cost fabrication process, little information exists on the sintering behavior of the structural silicide Mosi2. The sintering of commercial Mosi2 powders in the range of 1-10 μm was investigated as a function of sintering temperature, sintering time, and sintering atmosphere. Initial densities for uniaxially cold pressed powders were in the range of 47-56% theoretical. A maximum sintered density of 90% of theoretical was achieved for 1 μm Mosi2 powders after sintering for 100 hours at 1600 °C in an argon atmosphere. Larger 10 μm Mosi2 powders achieved lower sintered densities under these conditions. Avenues to optimize the sintering behavior of Mosi2 are suggested.

scholarly journals ESTIMASI KANDUNGAN KARBON ATAS PERMUKAAN TANAH PADA HUTAN ALAM DAN HUTAN REHABILITASI MANGROVE TAMAN HUTAN RAYA NGURAH RAI BALI

2021 ◽  
Vol 15 (2) ◽  
pp. 222
Author(s):  
Made Suartana ◽  
I Nyoman Merit ◽  
I Made Sudarma
Keyword(s):  
Carbon Content ◽  
Sampling Method ◽  
Carbon Potential ◽  
Natural Forest ◽  
Total Carbon ◽  
Density Level ◽  
Biomass Density ◽  
Total Carbon Content ◽  
Canopy Density ◽  
Forest Park

Mangroves are ecosystems that play an important role in absorbing and storing carbon from the air, one of which is in the form of mangrove vegetation biomass. As the largest mangrove area in Bali which consists of natural and rehabilitation vegetation, Taman Hutan Raya Ngurah Rai has a large potential for high carbon content. To determine the carbon potential of mangroves in natural and rehabilitation forests, a research was conducted using the purposive sampling method based on the canopy density level which was divided into 5 categories, namely very rare, rare, moderate, dense, very dense. Based on the results of measurements and calculations, the total carbon content of Ngurah Rai Grand Forest Park is 86.521,74 tons C, consisting of natural forest content 66.857,53 tons C and rehabilitation forest 19.664,21 tons C. Above ground carbon per hectare in natural forest was not significantly different from the above ground carbon per hectare in rehabilitation forest, these results indicate that the carbon content per hectare of rehabilitation forest over 20 years old is almost close to the carbon content per hectare in natural forest. The diameter of trees and vegetation types did not significantly affect the carbon content of mangroves, these results indicate that the increase in carbon stocks in each type of vegetation in natural and rehabilitation forests is in line with diameter growth. Keywords: Biomass; Density; Diameter; Canopy.

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