Geochemical characterization of the loess-paleosol sequence in northeast China

Sun, Zhong-Xiu; Jiang, Ying-Ying; Wang, Qiubing; Owens, Phillip R.

doi:10.1016/j.geoderma.2018.02.012

Cited by 15 publications

(14 citation statements)

References 38 publications

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“…Some researchers (Carraturo et al ., 2021; Vignesh et al ., 2021) have reviewed about additive manufacturing (AM) that is used to create medical implants. Other researchers (Sun et al ., 2018; Wang et al ., 2018) used a PBF on a type of stainless steel called SS316 L. They were able to achieve high strength and flexibility in the stainless steel, which is important for making reliable medical implants.…”

Section: Introductionmentioning

confidence: 89%

“…Some researchers (Carraturo et al, 2021;Vignesh et al, 2021) have reviewed about additive manufacturing (AM) that is used to create medical implants. Other researchers (Sun et al, 2018;Wang et al, 2018) used a PBF on a type of stainless steel called SS316 L. They were able to achieve high strength and flexibility in the stainless steel, which is important for making reliable medical implants. Jiang et al (2019) has utilized the concept of equivalent energy density (E * 0 ) which is a function of several parameters and selected three input process variables (viz, laser power (q), scanning speed (v) and hatch spacing (h)).…”

Section: Selective Laser Melting (Slm) Processmentioning

confidence: 99%

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Multi-objective optimization to specify optimal selective laser melting process parameters for SS316 L powder

Prasanth Kumar,

Boggarapu,

Narayana Murty

2023

MMMS

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PurposeThis paper adopts a modified Taguchi approach to develop empirical relationships to the performance characteristics (output responses) in terms of process variables and demonstrated their validity through comparison of test data. The method suggests a few tests as per the orthogonal array and provides complete information for all combinations of levels and process variables. This method also provides the estimated range of output responses so that the scatter in the repeated tests can be assessed prior to the tests.Design/methodology/approachIn order to obtain defect-free products meeting the required specifications, researchers have conducted extensive experiments using powder bed fusion (PBF) process measuring the performance indicators (namely, relative density, surface roughness and hardness) to specify a set of printing parameters (namely, laser power, scanning speed and hatch spacing). A simple and reliable multi-objective optimization method is considered in this paper for specifying a set of optimal process parameters with SS316 L powder. It was reported that test samples printed even with optimal set of input variables revealed irregular shaped, microscopic porosities and improper melt pool formation.FindingsFinally, based on detailed analysis, it is concluded that it is impossible to express the performance indicators, explicitly in terms of equivalent energy density (E_0ˆ*), which is a combination of multiple sets of selective laser melting (SLM) process parameters, with different performance indicators. Empirical relations for the performance indicators are developed in terms of SLM process parameters. Test data are within/close to the expected range.Practical implicationsBased on extensive analysis of the SS316 L data using modified Taguchi approach, the optimized process parameters are laser power = 298 W, scanning speed = 900 mm/s and hatch distance = 0.075 mm, for which the results of surface roughness = 2.77 Ra, relative density = 99.24%, hardness = 334 Hv and equivalent energy density is 4.062. The estimated data for the same are surface roughness is 3.733 Ra, relative density is 99.926%, hardness is 213.64 Hv and equivalent energy density is 3.677.Originality/valueEven though equivalent energy density represents the energy input to the process, the findings of this paper conclude that energy density should no longer be considered as a dependent process parameter, as it provides multiple results for the specified energy density. This aspect has been successfully demonstrated in this paper using test data.

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Section: Introductionmentioning

confidence: 89%

Section: Selective Laser Melting (Slm) Processmentioning

confidence: 99%

Multi-objective optimization to specify optimal selective laser melting process parameters for SS316 L powder

Prasanth Kumar,

Boggarapu,

Narayana Murty

2023

MMMS

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“…The mobility of elements during chemical weathering can be assessed by means of mass balance calculations. Mass balance interpretations have been applied for quantifying the mobility of elements in loess-paleosol sequences (e.g., Yang et al, 2006;Sun et al, 2018) as well as in other environments and materials (e.g., Girty et al, 2003;Campodonico et al, 2014;Girty et al, 2014;Campodonico et al, 2019). The Woronow and Love (1990) log-ratio technique was employed here to quantify the elemental fractionation and mass changes that occurred between loess and paleosols.…”

Section: Weathering Assessmentmentioning

confidence: 99%

“…Harnois, 1988), and the Plagioclase Index of Alteration (PIA; Fedo et al, 1995), among others. Likewise, mass balance estimations and trace elements ratios have also been used as proxies of paleo-weathering conditions (e.g., Yang et al, 2006;Tugulan et al, 2016;Sun et al, 2018). It is well known that weathering intensity is related to several factors such as climate, relief, biota, time, and the bedrock characteristics.…”

Section: Introductionmentioning

confidence: 99%

Geochemistry of a Late Quaternary loess-paleosol sequence in central Argentina: Implications for weathering, sedimentary recycling and provenance

2019

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A loess-paleosol sequence in the Pampean Plain, central Argentina was analyzed geochemically, in order to evaluate the weathering signature and sedimentary recycling as well as to analyze the origin of these loessic sediments. Corralito I sequence is composed of three paleosols and a buried soil separated by loess layers. The loess-paleosol sequence shows a similar geochemical composition throughout, suggesting that pedogenesis has not been intense enough to mask the chemical signature of the parent material. Weathering indices (CIA, CIW, PIA and LWI), elemental ratios (Rb/Sr, CaO/TiO 2 and Na 2 O/TiO 2), and the A-CN-K ternary diagram indicate incipient chemical alteration for this sequence, compatible with a weathering-limited regime. As expected, paleosols (CIAs~60) exhibit a slightly higher chemical alteration than loess layers (CIAs~58). Mass balance calculations reveal the losses of some major oxides (i.e., CaO, Na 2 O) and Sr in the buried soil and paleosols compared to its loess mantles, reflecting the weathering of plagioclase. Besides, the losses of K 2 O and Ba in the buried soil and paleosols I and II, when compared to its loess layers, suggest the chemical alteration of Kfeldspar. The chemical alteration of volcanic glass is evidenced by the relative losses of As in almost all levels. Conversely, the relative gains of Fe 2 O 3 and MgO reveal that pyroxenes and amphiboles or Fe oxy-hydroxides are concentrated in paleosols and the buried soil compared to its loess mantles. The geochemical approach used to constrain the origin of these Pampean Plain loessic sediments indicates they derive mainly from the Andean region. Conversely, the Pampean ranges, the Paraná River basin and Uruguayan Precambrian outcrops, which were pointed out as minor local sources, do not contribute significantly to the loess deposits. This work also shows that Corralito I loess-paleosol sequence and other loess samples from Argentina do not evidence sedimentary recycling, suggesting that these Pampean Plain loess deposits are mainly composed by young materials derived from undifferentiated volcanic rocks. The chemical composition of loessic sediments reveals the composition of the dust sources and reflects the modifications induced during transport and post-depositional weathering (e.g., Ahmad and Chandra, 2013). Different geochemical approaches have been used to analyze chemical weathering and provenance in loess-paleosol sequences in various regions of the world (e.g.,

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“…The interpretation of loess records in this area will help to expand the current understanding of the temporal and spatial evolution of the loess distribution in the context of the global loess distribution and climate research (Sun, Owens, et al, 2016;Vandenberghe et al, 2006). The current understanding of the temporal and spatial evolution of the loess distribution in this area is very poor (Sun et al, 2018b;Xie et al, 2019;Zeng et al, 2011) compared with other well-documented loess-palaeosol sequences in China (An, 2000;Liu, 1985;Liu & Ding, 1998). Moreover, the peculiar monsoon regime has triggered uniquely enhanced pedogenesis (Gallet et al, 1996;Hall & Anderson, 2000;Jahn et al, 2001;Muhs, 2018;Muhs et al, 2001).…”

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confidence: 99%

Iron pools of the typical loess–palaeosol sequence and their environmental significance in northeastern China

Sun,

Wang,

Jiang

et al. 2023

Earth Surf Processes Landf

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The iron content can be used as a proxy for the intensity of weathering and pedogenesis, which reflect long‐term climate cycles and short‐term climate fluctuations and events. In this study, a typical loess–palaeosol sequence for 19.85 m in thickness deposited since 423 ka BP in northeastern China was investigated, and its iron pools were determined. The results reveal that with increasing depth, the abundances of different forms of iron are consistent with the changes in the magnetic susceptibility. Iron (Fe) in all forms is more abundant in the palaeosol than in the loess. The silicate‐bound Fe pool (Fer = Fet − Fed) accounts for 60.4% of the total Fe (Fet), indicating weak pedogenesis. The Fe in the crystalline oxides (Fec = Fed − Feo) is predominantly free Fe (Fed), with a crystallinity [Fey = (Fed − Feo) × 100 / Fed] of as high as 97.2%. The coefficients of variation of the different forms of iron associated with the soil depth are as follows: Fec > Fed > poorly crystalline Fe (Feo) > Fer > Fet. The distribution of the forms of Fe throughout the profile is a clear indicator of the pedogenesis. The Fed, Fec, and Fe freeness (freeness = Fed × 100 / Fet) correlate with the magnetic susceptibility. The neoformation of iron (Fe) oxides was closely related to the degree of pedogenesis. More crystalline Fe oxides were found in the soil layers corresponding to warm interglacial periods. We detected variations in the abundance of the Fe pools for characterizing climate fluctuations that occurred in a short period of time. In this study, we demonstrated that when used in combination with dating techniques, morphological development indices, and magnetic susceptibility, the measurement of soil Fe pools can be extremely useful for tracing the iron evolution in the Earth's critical zone and reconstructing past climatic events in loess–palaeosol sequences.

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Geochemical characterization of the loess-paleosol sequence in northeast China

Cited by 15 publications

References 38 publications

Multi-objective optimization to specify optimal selective laser melting process parameters for SS316 L powder

Multi-objective optimization to specify optimal selective laser melting process parameters for SS316 L powder

Geochemistry of a Late Quaternary loess-paleosol sequence in central Argentina: Implications for weathering, sedimentary recycling and provenance

Iron pools of the typical loess–palaeosol sequence and their environmental significance in northeastern China

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