scholarly journals Effect of Holding Time on Populations of Microparticles in Spheroidal Graphite Irons

2022 ◽  
Author(s):  
L. Michels ◽  
A. J. F. Pires ◽  
C. A. S. Ribeiro ◽  
B. Kroka ◽  
E. G. Hoel ◽  
...  
Keyword(s):  
Ostwald Ripening ◽  
Holding Time ◽  
Spheroidal Graphite ◽  
Size Distributions ◽  
Statistical Parameters ◽  
Silicon Alloys ◽  
Graphite Phase ◽  
Central Hypothesis ◽  
2D To 3D ◽  
Number Of Particles

AbstractNon-metallic microparticles in spheroidal graphite irons are a product of the inoculation and the Mg-treatment of the liquid melt. Besides the influence on the mechanical properties of these iron–carbon–silicon alloys, they are also responsible for the nucleation and the morphology of the graphite phase. The present investigation is undertaken to study holding time effects of a (Ba, Ca, Al)–ferrosilicon (called Ba-inoculant) and (Ca, Al)–ferrosilicon (called Ca-inoculant) inoculants on the overall distribution of microparticles. Using the 2D to 3D conversions method, which is typically used for graphite nodules, the non-metallic microparticles’ statistical parameters, such as size distributions and number densities, are quantified. The total number of particles is similar after Mg-treatment and inoculation for Ca-inoculant but not for Ba-inoculated samples, which lose approximately 25 pct of microparticles after 1 minute of holding time. Iron treated with the Ca-inoculant loses about 37 pct of its nodules after 5 minutes, while the Ba-inoculated melts maintain their performance even after 10 minutes. Based on extrapolating the trend of the undercooling, Ba-inoculated samples would reach the uninoculated undercooling values in 48 minutes, while Ca-inoculated samples in only 11 minutes. By evaluating the size distributions of the non-metallic microparticles, the Ostwald ripening hypothesis or particle aggregation can be verified. The results suggest that sulfides are more critical for graphite nucleation since they can be correlated with the graphite number densities. However, due to the small difference in the microparticle population of the uninoculated sample with Ca-inoculated samples, other aspects of the fading mechanism need to be considered, such as transient metastable states, since the central hypothesis of loss of inclusions cannot alone explain the decrease in the nucleation frequency of graphite.

Effect of isothermal process parameters on semi-solid microstructure of chip-based Al–Cu–Mn–Ti alloy prepared by SIMA method

2020 ◽  
Vol 34 (33) ◽  
pp. 2050385
Author(s):  
Ye Wang ◽  
Maoliang Hu ◽  
Hongyu Xu ◽  
Zesheng Ji ◽  
Xuefeng Wen ◽  
...  
Keyword(s):  
Process Parameters ◽  
Ostwald Ripening ◽  
Isothermal Holding ◽  
Treatment Temperature ◽  
Holding Time ◽  
Isothermal Treatment ◽  
Isothermal Process ◽  
Semi Solid ◽  
Average Size ◽  
Relationship Of

A typical Al–Cu–Mn–Ti aluminum alloy chip was adopted to prepare semi-solid billets by a Strain-Induced Melt Activation (SIMA) method, and the effects of isothermal process parameters on the semi-solid microstructure evolution of the alloy were investigated in this work. The result showed that semi-solid billets with highly spheroidal and homogeneous fine grains could be prepared from chips by the SIMA method. With the increase of isothermal temperature, the finer and near-spherical grains are obtained, the grains coarsen and became ellipse at 903 K because of the coarsening mechanisms of coalescence and Ostwald ripening. The relationship of isothermal holding time and grains size followed the LSW theory well, and more spherical microstructure can be brought by prolonging the holding time until 3000 s. Thus, the optimal isothermal treatment temperature is 893 K and holding time is 3000 s, the corresponding average size and roundness of grains are 137 [Formula: see text]m and 1.108, respectively.

scholarly journals Henton Morrogh CBE FRS FREng. 29 September 1917 – 20 September 2003

2005 ◽  
Vol 51 ◽  
pp. 303-314
Author(s):  
E. Raymond Evans
Keyword(s):  
Cast Iron ◽  
Working Life ◽  
Spheroidal Graphite ◽  
Research Association ◽  
Graphite Phase ◽  
Unique Character ◽  
Structure Properties

Henton Morrogh devoted the whole of his working life to the study of cast iron, its structure, properties, applications and aspects of its production. He was particularly responsible for the development of techniques for preparing microspecimens to a state of perfection, which enabled him to study the morphology of the graphite phase, and he played a major role in the development of the revolutionary as–cast spheroidal graphite irons.He progressed from apprenticeship with British Cast Iron Research Association (BCIRA) to becoming its Director and was primarily responsible for the success of this Association and in establishing its worldwide reputation. He was a modest man, generous in the encouragement of his staff to perform research and to apply the results to the benefit of the iron founding industry. In short, it could be said that Henton Morrogh was the BCIRA and the BCIRA was Henton Morrogh–such was his unique character.

Doping effects on coarsening of Y2BaCuO5 phase in liquid

1993 ◽  
Vol 8 (6) ◽  
pp. 1240-1246 ◽  
Author(s):  
Teruo Izumi ◽  
Yuichi Nakamura ◽  
Yuh Shiohara
Keyword(s):  
Ostwald Ripening ◽  
Average Diameter ◽  
Holding Time ◽  
Doping Effects ◽  
Thomson Coefficient

The coarsening rate of Y2BaCuO5 (211) phase in liquid was investigated by observations of samples which were held at 1070 °C for different holding times. The 211 phase formed rod-like shapes, and the diameters increased with the increase in the holding time. The average diameter increased in proportion to t1/3 (t, holding time). This means that coarsening can be explained by the modified Ostwald ripening theory. Platinum-doping suppressed the coarsening rate and alumina-doping promoted it. However, both coarsening rates were also proportional to t1/3. The changes in the rate can be represented by the changes of the DLΓ value (DL, diffusivity in liquid and Γ, Gibbs—Thomson coefficient) using the Ostwald ripening theory; i.e., the value is made lower by platinum-doping and higher by alumina-doping.

scholarly journals Particle and gaseous emissions from individual diesel and CNG buses

2013 ◽  
Vol 13 (10) ◽  
pp. 5337-5350 ◽  
Author(s):  
Å. M. Hallquist ◽  
M. Jerksjö ◽  
H. Fallgren ◽  
J. Westerlund ◽  
Å. Sjödin
Keyword(s):  
Emission Factors ◽  
Constant Speed ◽  
Particulate Filter ◽  
High Time Resolution ◽  
Exhaust Gas ◽  
Size Distributions ◽  
Gaseous Emissions ◽  
Diesel Buses ◽  
Speed Mode ◽  
Number Of Particles

Abstract. In this study size-resolved particle and gaseous emissions from 28 individual diesel-fuelled and 7 compressed natural gas (CNG)-fuelled buses, selected from an in-use bus fleet, were characterised for real-world dilution scenarios. The method used was based on using CO2 as a tracer of exhaust gas dilution. The particles were sampled by using an extractive sampling method and analysed with high time resolution instrumentation EEPS (10 Hz) and CO2 with a non-dispersive infrared gas analyser (LI-840, LI-COR Inc. 1 Hz). The gaseous constituents (CO, HC and NO) were measured by using a remote sensing device (AccuScan RSD 3000, Environmental System Products Inc.). Nitrogen oxides, NOx, were estimated from NO by using default NO2/NOx ratios from the road vehicle emission model HBEFA3.1. The buses studied were diesel-fuelled Euro III–V and CNG-fuelled Enhanced Environmentally Friendly Vehicles (EEVs) with different after-treatment, including selective catalytic reduction (SCR), exhaust gas recirculation (EGR) and with and without diesel particulate filter (DPF). The primary driving mode applied in this study was accelerating mode. However, regarding the particle emissions also a constant speed mode was analysed. The investigated CNG buses emitted on average a higher number of particles but less mass compared to the diesel-fuelled buses. Emission factors for number of particles (EFPN) were EFPN, DPF = 4.4 ± 3.5 × 1014, EFPN, no DPF = 2.1 ± 1.0 × 1015 and EFPN, CNG = 7.8 ± 5.7 ×1015 kg fuel−1. In the accelerating mode, size-resolved emission factors (EFs) showed unimodal number size distributions with peak diameters of 70–90 nm and 10 nm for diesel and CNG buses, respectively. For the constant speed mode, bimodal average number size distributions were obtained for the diesel buses with peak modes of ~10 nm and ~60 nm. Emission factors for NOx expressed as NO2 equivalents for the diesel buses were on average 27 ± 7 g (kg fuel)−1 and for the CNG buses 41 ± 26 g (kg fuel)−1. An anti-relationship between EFNOx and EFPM was observed especially for buses with no DPF, and there was a positive relationship between EFPM and EFCO.

scholarly journals GRAIN-SIZE STATISTICAL PARAMETERS OF SANDY SEDIMENT IN KUALA GIGIENG, ACEH BESAR DISTRICT

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Syahrul Purnawan ◽  
Haekal A. Haridhi ◽  
Ichsan Setiawan ◽  
. Marwantim
Keyword(s):  
Grain Size ◽  
Sediment Load ◽  
Distribution Patterns ◽  
Sandy Sediment ◽  
Size Distributions ◽  
Statistical Parameters ◽  
Sediment Distribution ◽  
Coarse Grains ◽  
Load Transport ◽  
Grain Size Distributions

Study of sediment distribution at Kuala Gigieng was to assess the information of sediment related to the occurrence of hydro-oceanographic processes. The sediment samples were collected from nine stations using coring method. Granulometric method was used to analyze the grain size distributions. The results showed different sediment distribution patterns in each area at estuary Kuala Gigieng. The outer area of estuary indicated skewed to coarse grains, while at the inner area of estuary indicated skewed to fine grains. Different sediment load transport process was suggested as the cause of differentiated sediment characters.   Keywords: granulometry, grain size, sediment statistic, Kuala Gigieng

scholarly journals Technological pecularities of producing cast iron with spherical graphite using a fast-cooled copper-magnesium ligature

2020 ◽  
pp. 15-21
Author(s):  
A. G. Slutsky ◽  
I. L. Kulinich ◽  
V. A. Sheinert ◽  
V. A. Stefanovich ◽  
R. E. Trubitsky ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cast Iron ◽  
Chemical Composition ◽  
Magnesium Alloys ◽  
High Strength ◽  
Favorable Effect ◽  
Maximum Effect ◽  
Spheroidal Graphite ◽  
Graphite Phase ◽  
Spherical Graphite

Various modifiers are used for non-furnace processing of cast iron. Some of them are designed for inoculating modification, which improves mechanical properties and eliminates the appearance of whiteness in castings, while others are designed for spheroidizing processing, in particular for producing cast iron with spherical and vermicular graphite. Some have both spheroidizing and inoculating properties. The main part of inoculating and spheroidizing modifiers is made on iron-silicon, Nickel and copper bases.In addition to the chemical composition, the size of the modifier particles, as well as their shape, are of great importance for modification. The optimal size of the fraction depends significantly on the non-furnace processing technology. Thus, for the larger the bucket and the longer the casting the longer the modification effect is required. One of the methods to achieve this is to increase the particle size of the modifier to 50 mm. When intraform processing of cast iron with spherical and vermicular graphite, magnesium-containing modifiers have strict limits on the upper size (4...5 mm), and in addition, the content of small fractions (less than 0.6...1 mm) is not allowed.The use of «heavy» magnesium-containing ligatures for spheroidizing modification of cast iron in order to obtain higher physical and mechanical properties has scientific and practical interest. Numerous studies show that for maximum effect the formation of the structure of the spheroidal graphite, dispersed pearlite metallic base of SGI (spheroidal graphite iron) relevant question is not only selection of the chemical composition of magnesium alloys, but also of the fractional composition, as well as effective method of input into the liquid melt.The purpose of this work was to study the technological features of obtaining cast iron with spherical graphite by bucket modification of copper-magnesium ligature.The researchers used a Leo–1420 scanning microscope, a Polam l-213 optical microscope, and a VEGA II LMU electron microscope with an INCA ENERGY 350 microanalyzer. High-speed induction melting plant, a set of equipment for analyzing the technological and mechanical properties of high-strength cast iron were used.Earlier experimental studies have shown the real possibility of obtaining in the laboratory a «heavy» copper-magnesium alloys as the alloying of magnesium metal with copper, followed by rapid cooling with use of rolling and plastic deformation of powder alloys. Analysis of test results of samples of such alloys showed that it depends on the value of its additives into liquid iron in the structure of formed graphite phase in compacted and globular form. At the same time, the metal base of cast iron is additionally alloyed with copper, which has a favorable effect on the strength characteristics of SGI.However, an urgent problem is the possibility of the appearance of a cementite phase in the structure of high-strength cast iron as a result of its increased supercooling due to the process of spheroidization of the graphite phase. This phenomenon is compounded by the fact that the copper-magnesium ligature, in contrast to the «light» ligature, does not contain silicon active graphitizer. This feature must be taken into account when obtaining high-strength cast iron of high grades.

scholarly journals PECULIARITIES OF THE DIAMETER DISTRIBUTIONS OBTAINED AT SUBMILISECOND DURATION OF DISCHARGE PULSES SPARK-EROSIVE ALUMINUM PARTICLES AND CAVERNS ON THE SURFACE OF ITS GRANULES

2021 ◽  
Vol 2021 (1) ◽  
pp. 10-22
Author(s):  
N.A. Shidlovska ◽  
◽  
S.M. Zakharchenko ◽  
A.O. Perekos ◽  
◽  
...  
Keyword(s):  
Single Mode ◽  
Random Variable ◽  
Size Distributions ◽  
Statistical Parameters ◽  
Aluminum Particles ◽  
Mode Size ◽  
Log Normal ◽  
Log Normal Distribution ◽  
Gauss Distribution ◽  
Diameter Distributions

The conditions and technique for obtaining single-mode size distributions of spark-erosive aluminum particles are given. The statistical parameters of the size distributions of spark-erosive aluminum particles and caverns on the surface of its granules, obtained at a submilisecond duration of discharge pulses were calculated. A comparative analysis of the volumes of metal of erosion caverns and particles is carried out. The agreement of the diameter distributions of spark-erosive particles and caverns obtained in practice with the following theoretical distributions of a continuous random variable: Gauss, Weibull, the integral of the Rosin-Rammler function, and also log-normal distribution is verified. In this case, the parameters of theoretical distributions were calculated both by the statistical parameters of the distributions obtained in practice, and by the criterion of the smallest value of the average module of the relative deviation of the theoretical and practical distributions. It has been shown that for the values of the parameters of theoretical distributions that correspond to the statistical parameters of practical distributions, the distribution of erosive particles by diameters is in the best agreement with the Gauss distribution, and the caverns – with the distribution of integral of the Rosin-Rammler function. References 27, figures 2, tables 3.

scholarly journals GRAIN-SIZE STATISTICAL PARAMETERS OF SANDY SEDIMENT IN KUALA GIGIENG, ACEH BESAR DISTRICT

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Syahrul Purnawan ◽  
Haekal A. Haridhi ◽  
Ichsan Setiawan ◽  
. Marwantim
Keyword(s):  
Grain Size ◽  
Sediment Load ◽  
Distribution Patterns ◽  
Sandy Sediment ◽  
Size Distributions ◽  
Statistical Parameters ◽  
Sediment Distribution ◽  
Coarse Grains ◽  
Load Transport ◽  
Grain Size Distributions

<p><em>Study of sediment distribution at Kuala Gig</em><em>i</em><em>eng was to assess the information of sediment related to the occurrence of</em><em> </em><em>hydro-oceanographic processes. The sediment samples were collected from nine stations using coring method. Granulometri</em><em>c</em><em> method was used to analyze the grain size distributions. The results showed different sediment distribution patterns in each area at estuary Kuala Gig</em><em>i</em><em>eng. The outer area of estuary indicated skewed to coarse grains, while at the inner area of estuary indicat</em><em>e</em><em>d skewed to fine grains. Different sediment load transport process was suggested as the cause of differentiate</em><em>d</em><em> sediment characters.</em><em> </em></p> <p> </p> <strong><em>Keywords: </em></strong><em>granulometry, grain size, sediment statistic, Kuala Gigieng</em>

Sign in / Sign up

Export Citation Format

Share Document