scholarly journals Increasing the tribological properties of the sur-face layer of cast iron by treatment in the envi-ronment of overheated steam of aqueous solution

2021 ◽  
pp. 123
Author(s):  
Larisa Timofeeva ◽  
Sergey Timofeev ◽  
Liudmyla Voloshyna ◽  
Maksym Kolesnyk
Keyword(s):  
Aqueous Solution ◽  
Surface Layer ◽  
Cast Iron ◽  
Superheated Steam ◽  
Multilayer Coating ◽  
Water Soluble ◽  
Metal Base ◽  
Friction Moment ◽  
The Matrix ◽  
The Impact

The formation of the surface layer of cast iron during the processing of cast iron in the environment of superheated steam of an aqueous solution of salts is considered. An ecologically cleaner method of chemical-thermal treatment is offered. The article considers the surface layer obtained in the environment of superheated steam of an aqueous solution of water-soluble salts of ammonium molybdic acid. The layer is formed on the surface of the matrix and around the graphite inclusions. The impact of temperature on the formation of a multilayer coating by increasing the temperature in contact with the metal surface is the dissociation of chemical compounds in solution, with the formation of atomic oxygen, sulfur, nitrogen, molybdenum. The formation of the surface layer occurred not only on a metal base, but also on the boundaries of graphite, both lamellar and globular, coming to the surface of the metal without breaking the solid layer. It is established that as a result of interaction of technological parameters of temperature, holding time and concentration of saturated medium graphite in the surface layer changes its shape, becoming spherical, although in the matrix it had a lamellar shape. It is multiphase and contains soft and hard structural components. Comparative studies have shown that the wear rate of untreated cast iron is much higher than that of treated cast iron, and reaches 0.8 ∙ 10-4 μm/km at a load of 400 N. This increases the wear resistance of cast iron and at the same time improves the workability reducing the coefficient of friction. The effect of the coating on the workability show that the stabilization of the friction moment occurs faster in samples with a multilayer coating. Thus, for gray cast iron with lamellar graphite, the stabilization time of the friction moment in a multilayer coating is 0.6 h compared with 2 h for a single layer coating; in high-strength cast iron it is, respectively, 5.2 and 6.3 hours.

Study on the Microstructures and Wear Resistance of ZG30Cr Steel Surface Layer

2011 ◽  
Vol 704-705 ◽  
pp. 23-27
Author(s):  
Shu Li Wang ◽  
Ai Qin Wang ◽  
Jing Pei Xie
Keyword(s):  
Particle Size ◽  
Wear Resistance ◽  
Surface Layer ◽  
Cast Iron ◽  
Steel Surface ◽  
Layer Structure ◽  
Iron Layer ◽  
Wear Properties ◽  
Metallurgical Bonding ◽  
The Matrix

In this paper ,the WC and high-Cr Cast Iron layer were obtained on the surface of ZG30Cr steel by casting-penetrating process, the organization and wear properties of penetrating layer were studied.The results show that the layer is dense, without pores, slag and other defects, the penetrating layer and substrate are metallurgical bonding. When 30 %WC and 70 % Cr-Fe with 100～120 mesh are added to permeability agent ,the penetrating layer has the best wear resistance, is 6.8 times the matrix materials. Keywords: The layer structure; Particle size; Wear resistance

Study on Erosion Wear Property of Nickel-Chromium Cast Iron

2013 ◽  
Vol 575-576 ◽  
pp. 535-538
Author(s):  
Jing Pei Xie ◽  
Li Jun Zhang ◽  
Ai Qin Wang ◽  
Xing Hai Shao
Keyword(s):  
Cast Iron ◽  
Wear Behavior ◽  
Strong Acid ◽  
Impact Angle ◽  
Homogeneous Distribution ◽  
Test Machine ◽  
Wear Property ◽  
Erosion Wear ◽  
The Matrix ◽  
The Impact

The influences of the impact angle and the corrosive agent acidity on low-chromium and nickel contained cast iron were studied in the behavior of erosion wear. The wear rule was summarized and the mechanics of the erosion wear behavior were analyzed in this thesis. Erosion wear experiments were carried on MCF-30 erosion test machine, and then the structure and surface morphology of the samples were analyzed by Scanning Electron Microscopy (SEM). The results showed that the alloy carbide (Fe, Cr)3C was generated by a kind of reticulate distribution in the matrix after oil quench at 960°C and temper at 250°C. The continuous and homogeneous distribution, just like the skeleton of the material, enhanced the wear resistance. The shape of erosion wear curve was M at different impact angles. The biggest wear rate occurred at a 60-degree impact angle. The erosion wear property was greatly affected by the strong acid, but it can be ignored when pH3.

Microstructure and Property of the New Type White Cast Iron

2008 ◽  
Vol 51 ◽  
pp. 31-40 ◽  
Author(s):  
Xian Liang Zhou ◽  
Xiao Zhen Hua ◽  
Jian Yun Zhang ◽  
Yong Jin Tang ◽  
Qing Jun Chen
Keyword(s):  
Wear Resistance ◽  
Cast Iron ◽  
White Cast Iron ◽  
Heating Temperature ◽  
Xrd Analysis ◽  
Cr Content ◽  
The Matrix ◽  
New Type ◽  
Si Content ◽  
The Impact

The influences of the different Si (0.723%~4.5%) and Cr (2.0%~8.0%) contents on the microstructures and properties of Cr-Si-Mn white cast iron were investigated. It is shown that with increasing of amounts of Si and Cr elements, carbide undergoes an evident change in the morphology from the continuous net to isolated stripe and becomes clearly finer, even forms chrysanthemum-like microstructure which is usually found in high Cr white cast iron. Additionally, the amounts of the carbides increase too. The XRD analysis shows that the carbides are a mixture of Fe3C and Fe7C3 phases. Furthermore, the hardness of carbide and matrix is also found to progressively increase with increasing of amounts of Si and Cr elements. The hardness of the matrix in as-cast white cast iron is over HV400, suggesting that the matrix consists of martensite and bainite phases. The impact toughness of the samples declines evidently when Si content excesses 3.0wt%. It is also revealed that the bainite matrix in the Si-Cr white cast iron has a higher impact abrasive wear resistance than others, which is almost not dependent upon heating temperature and cooling rate. When Cr content approaches 5wt%, the impact wear resistance of the new cast iron is comparable to that of the traditional high Cr cast iron.

scholarly journals Effects of Heat-Treatment on the Microstructure and Wear Resistance of a High-Chromium Cast Iron for Rolls

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Zhi-hong Guo ◽  
Fu-ren Xiao ◽  
Su-ling Lu ◽  
Han-yun Li ◽  
Bo Liao
Keyword(s):  
Wear Resistance ◽  
Cast Iron ◽  
Retained Austenite ◽  
Tempered Martensite ◽  
High Chromium ◽  
High Chromium Cast Iron ◽  
The Matrix ◽  
The Impact ◽  
Chromium Cast Iron ◽  
Martensite Matrix

The variations of microstructure and mechanical properties of a high-chromium cast iron for rolls were studied from as-cast to the final heat treatments. Results show that the as-cast microstructure of the HCCI consists of M7C3carbide, M23C6carbide, martensite matrix, and retained austenite. The large dendritic M7C3carbide surrounds the matrix, and the M23C6carbide is mainly distributed in the matrix. Part of M23C6carbide transforms to M7C3carbide and is dissolved in austenite during austenization at 1020°C. Thus, the amount of M23C6carbide decreases, whereas that of M7C3carbide increases after quenching; the highest hardness is also obtained. After tempering, the martensite transforms to a tempered martensite, and some carbide precipitates in the martensite matrix. The hardness also changes from HRC62.1, which corresponds to quenching, to HRC55.2 and HRC56.3, which correspond to once and twice tempering, respectively. However, tempering could improve the impact toughness and wear resistance of the HCCI.

scholarly journals Effect of High-Temperature Quenching on the Phase Composition, Structure, and Wear Resistance of Ni-Hard Chromium-Nickel Cast Iron

2021 ◽  
Vol 346 ◽  
pp. 02025
Author(s):  
M.A. Filippov ◽  
V.A. Sharapova ◽  
L.A. Moshechkova ◽  
S.O. Morozov
Keyword(s):  
Wear Resistance ◽  
Phase Composition ◽  
Cast Iron ◽  
Wear Test ◽  
Wear Testing ◽  
Quenching Temperature ◽  
Metal Base ◽  
X Ray ◽  
Hard Chromium ◽  
The Impact

Metallographic, micro-X-ray spectral and X-ray structural analyses have been carried out. The quenching temperature increase from 900 to 1150 °C leads to high abrasive wear resistance in Ni-hard chromium-nickel cast iron. The initial hardness decreased before the test from 60 to 35 HRC due to the fact that the phase composition of the metal base before the wear test changes during quenching from medium-carbon martensite with secondary cementite to retained metastable austenite. It contributes to increase the crack resistance of cast iron. Austenite turns into dispersed friction martensite on the working surface in the process of wear testing or operation, as a result of the impact of abrasive particles. This martensite together with a part of cementite provides a high level of hardening and operability of the cast iron secondary microstructure.

An SEM study of raphide crystal initials in the leaves of vitis (grape)

1995 ◽  
Vol 53 ◽  
pp. 984-985
Author(s):  
H. J. Arnott ◽  
M. A. Webb ◽  
L. E. Lopez
Keyword(s):  
Calcium Oxalate ◽  
Water Soluble ◽  
Calcium Oxalate Crystals ◽  
Calcium Oxalate Crystal ◽  
Oxalate Crystals ◽  
Large Numbers ◽  
Sem Study ◽  
The Matrix ◽  
Crystal Cells ◽  
Crystal Idioblast

Many papers have been published on the structure of calcium oxalate crystals in plants, however, few deal with the early development of crystals. Large numbers of idioblastic calcium oxalate crystal cells are found in the leaves of Vitis mustangensis, V. labrusca and V. vulpina. A crystal idioblast, or raphide cell, will produce 150-300 needle-like calcium oxalate crystals within a central vacuole. Each raphide crystal is autonomous, having been produced in a separate membrane-defined crystal chamber; the idioblast''s crystal complement is collectively embedded in a water soluble glycoprotein matrix which fills the vacuole. The crystals are twins, each having a pointed and a bidentate end (Fig 1); when mature they are about 0.5-1.2 μn in diameter and 30-70 μm in length. Crystal bundles, i.e., crystals and their matrix, can be isolated from leaves using 100% ETOH. If the bundles are treated with H2O the matrix surrounding the crystals rapidly disperses.

Genetic Variation: Impact on Folate (and Choline) Bioefficacy

2010 ◽  
Vol 80 (45) ◽  
pp. 319-329 ◽  
Author(s):  
Allyson A. West ◽  
Marie A. Caudill
Keyword(s):  
Carbon Metabolism ◽  
Genetic Variants ◽  
Plasma Homocysteine ◽  
Water Soluble ◽  
Gene Interactions ◽  
Dietary Folate ◽  
Methyl Donors ◽  
Common Genetic Variants ◽  
One Carbon Metabolism ◽  
The Impact

Folate and choline are water-soluble micronutrients that serve as methyl donors in the conversion of homocysteine to methionine. Inadequacy of these nutrients can disturb one-carbon metabolism as evidenced by alterations in circulating folate and/or plasma homocysteine. Among common genetic variants that reside in genes regulating folate absorptive and metabolic processes, homozygosity for the MTHFR 677C > T variant has consistently been shown to have robust effects on status markers. This paper will review the impact of genetic variants in folate-metabolizing genes on folate and choline bioefficacy. Nutrient-gene and gene-gene interactions will be considered along with the need to account for these genetic variants when updating dietary folate and choline recommendations.

Enantioselective Recognition of Chiral Guests by the Water-Soluble Chiral Keplerate {Mo132} Spherical Capsule with 30 Inner Lactate Ligands

2019 ◽  
Author(s):  
Nancy Watfa ◽  
Weimin Xuan ◽  
Zoe Sinclair ◽  
Robert Pow ◽  
Yousef Abul-Haija ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Chiral Recognition ◽  
Association Constants ◽  
Water Soluble ◽  
Enantioselective Recognition ◽  
H Nmr ◽  
Dosy Nmr ◽  
Spherical Capsule ◽  
Surface Pores ◽  
Guest Chemistry

Investigations of chiral host guest chemistry are important to explore recognition in confined environments. Here, by synthesizing water-soluble chiral porous nanocapsule based on the inorganic metal-oxo Keplerate-type cluster, {Mo<sub>132</sub>} with chiral lactate ligands with the composition [Mo<sub>132</sub>O<sub>372</sub>(H<sub>2</sub>O)<sub>72</sub>(<i>x-</i>Lactate)<sub>30</sub>]<sup>42-</sup> (<i>x</i> = D or L), it was possible to study the interaction with a chiral guest, L/D-carnitine and (<i>R</i>/<i>S</i>)-2-butanol in aqueous solution. The enantioselective recognition was studied by quantitative <sup>1</sup>H NMR and <sup>1</sup>H DOSY NMR which highlighted that the chiral recognition is regulated by two distinct sites. Differences in the association constants (K) of L- and D-carnitine, which, due to their charge, are generally restricted from entering the interior of the host, are observed, indicating that their recognition predominantly occurs at the surface pores of the structure. Conversely, a larger difference in association constants (K<i><sub>S</sub></i>/K<i><sub>R</sub></i> = 3) is observed for recognition within the capsule interior of (<i>R</i>)- and (<i>S</i>)-2-butanol.

Impact Strength, Flexural Modulus and Wear Rate of PMMA Composites Reinforced by Eggshell Powders

2020 ◽  
Vol 38 (7A) ◽  
pp. 960-966
Author(s):  
Aseel M. Abdullah ◽  
Hussein Jaber ◽  
Hanaa A. Al-Kaisy
Keyword(s):  
Impact Strength ◽  
Wear Rate ◽  
Flexural Modulus ◽  
Matrix Material ◽  
Weight Fraction ◽  
Pure Pmma ◽  
Calcination Process ◽  
The Matrix ◽  
The Impact ◽  
Interface Bond

In the present study, the impact strength, flexural modulus, and wear rate of poly methyl methacrylate (PMMA) with eggshell powder (ESP) composites have been investigated. The PMMA used as a matrix material reinforced with ESP at two different states (including untreated eggshell powder (UTESP) and treated eggshell powder (TESP)). Both UTESP and TESP were mixed with PMMA at different weight fractions ranged from (1-5) wt.%. The results revealed that the mechanical properties of the PMMA/ESP composites were enhanced steadily with increasing eggshell contents. The samples with 5 wt.% of UTESP and TESP additions give the maximum values of impact strength, about twice the value of the pure PMMA sample. The calcination process of eggshells powders gives better properties of the PMMA samples compared with the UTESP at the same weight fraction due to improvements in the interface bond between the matrix and particles. The wear characteristics of the PMMA composites decrease by about 57% with increases the weight fraction of TESP up to 5 wt.%. The flexural modulus values are slightly enhanced by increasing of the ESP contents in the PMMA composites.

scholarly journals Desiccation time and rainfall control gaseous carbon fluxes in an intermittent stream

2021 ◽  
Author(s):  
Maria Isabel Arce ◽  
Mia M. Bengtsson ◽  
Daniel von Schiller ◽  
Dominik Zak ◽  
Jana Täumer ◽  
...  
Keyword(s):  
Water Soluble ◽  
Intermittent Flow ◽  
Dry Period ◽  
Intermittent Stream ◽  
Aerobic Activity ◽  
Water Soluble Organic Carbon ◽  
Soluble Organic Carbon ◽  
Microbial C ◽  
Global Biogeochemical Cycles ◽  
The Impact

AbstractDroughts are recognized to impact global biogeochemical cycles. However, the implication of desiccation on in-stream carbon (C) cycling is not well understood yet. We subjected sediments from a lowland, organic rich intermittent stream to experimental desiccation over a 9-week-period to investigate temporal changes in microbial functional traits in relation to their redox requirements, carbon dioxide (CO2) and methane (CH4) fluxes and water-soluble organic carbon (WSOC). Concurrently, the implications of rewetting by simulated short rainfalls (4 and 21 mm) on gaseous C fluxes were tested. Early desiccation triggered dynamic fluxes of CO2 and CH4 with peak values of 383 and 30 mg C m−2 h−1 (mean ± SD), respectively, likely in response to enhanced aerobic mineralization and accelerated evasion. At longer desiccation, CH4 dropped abruptly, likely because of reduced abundance of anaerobic microbial traits. The CO2 fluxes ceased later, suggesting aerobic activity was constrained only by extended desiccation over time. We found that rainfall boosted fluxes of CO2, which were modulated by rainfall size and the preceding desiccation time. Desiccation also reduced the amount of WSOC and the proportion of labile compounds leaching from sediment. It remains questionable to which extent changes of the sediment C pool are influenced by respiration processes, microbial C uptake and cell lysis due to drying-rewetting cycles. We highlight that the severity of the dry period, which is controlled by its duration and the presence of precipitation events, needs detailed consideration to estimate the impact of intermittent flow on global riverine C fluxes.

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