Deposition Units Research Articles

Wire Oscillating Laser Additive Manufacturing of 2319 Aluminum Alloy: Optimization of Process Parameters, Microstructure, and Mechanical Properties

In this study, a wire oscillating laser additive manufacturing (O-WLAM) process was used to deposit 2319 aluminum alloy samples. The optimization of the deposition process parameters made it possible to obtain samples with smooth surfaces and extremely low porosities. The effects of the deposition parameters on the formability and evolution of the microstructure and mechanical properties before and after heat treatment were studied. The oscillating laser deposition of 2319 aluminum alloy, especially the circular oscillation mode, significantly reduced the porosity and improved the process stability and formability compared with non-oscillating laser deposition. There were clear boundaries between the deposition units in the deposition state, the interior of which was dominated by columnar crystals with many rod- and point-shaped precipitates. After the heat treatment, the θ phase was significantly dissolved. The residual dot- and rod-shaped θ ' phases were dispersedly distributed, exhibiting an obvious precipitation-hardening effect. The samples in the as-deposited state had a tensile strength of 245–265 MPa, an elongation of approximately 12.6%, and an 87 HV microhardness. After heat treatment at 530°C for 20 h and aging at 175°C for 18 h, the tensile strength, elongation, and microhardness reached 425–440 MPa, approximately 10%, and 153 HV, respectively. The performance improved significantly without significant anisotropy. Compared with the samples produced by wire arc additive manufacturing (WAAM), the tensile strength increased by approximately 10%, and the strength and microhardness were significantly improved.

Seismic Sequence Stratigraphic Sub-Division Using Well Logs and Seismic Data of Taranaki Basin, New Zealand

This study focuses on the sequence stratigraphy and the dominated seismic facies in the Central Taranaki basin. Four regional seismic sequences namely SEQ4 to SEQ1 from bottom to top and four boundaries representing unconformities namely H4 to H1 from bottom to top have been traced based on the reflection terminations. This was validated using well logs information. An onlapping feature on the seismic section indicates a new perspective surface separated between the upper and lower Giant formation, which indicates a period of seawater encroachment. This study focused extensively on deposition units from SEQ4 to SEQ1. The seismic facies, isochron map, and depositional environment were determined, and the system tract was established. This study was also able to propose a new perspective sequence stratigraphy framework of the basin and probable hydrocarbon accumulations and from the general geological aspect, SA-Middle Giant Formation (SEQ3) could act as potential traps.

Study on Reservoir Heterogeneity of Putaohua Oil Layer in Gulongnan Area

Putaohua oil layer is the main target layer in gulongnan area. The reservoir is mainly sheet sand with thin thickness, heavy mud content and poor physical properties. In recent years, the development effect of different blocks in this area is quite different. In this paper, the reservoir heterogeneity in Gulongnan area and each block is studied to provide reliable geological basis for improving oilfield development effect. Through the analysis of intra-layer, inter-layer and plane heterogeneity, it is considered that the overall reservoir heterogeneity in Gulongnan area is strong. In terms of deposition units, the heterogeneity of PI1, PI3 and PI6 is relatively strong, while the heterogeneity of PI2 and PI7 is relatively weak, and the remaining units are in between. In terms of zoning, the heterogeneity in G6 block is weak, the heterogeneity in M1 and A1 blocks is strong, and the heterogeneity in D1 block is the strongest. The application of heterogeneity analysis results provides strong support for promoting oil well effectiveness and delaying water breakthrough time.

Plasma spray–physical vapor deposition toward advanced thermal barrier coatings: a review

Plasma spray–physical vapor deposition (PS–PVD) is a unique technology that enables highly tailorable functional films and coatings with various rare metal elements to be processed. This technology bridges the gap between conventional thermal spray and vapor deposition and provides a variety of coating microstructures composed of vapor, liquid, and solid deposition units. The PS–PVD technique serves a broad range of applications in the fields of thermal barrier coatings (TBCs), environmental barrier coatings (EBCs), oxygen permeable films, and electrode films. It also represents the development direction of high-performance TBC/EBC preparation technologies. With the PS–PVD technique, the composition of the deposition unit determines the microstructure of the coating and its performance. When coating materials are injected into a nozzle and transported into the plasma jet, the deposition unit generated by a coating material is affected by the plasma jet characteristics. However, there is no direct in situ measurement method of material transfer and deposition processes in the PS–PVD plasma jet, because of the extreme conditions of PS–PVD such as a low operating pressure of ~ 100 Pa, temperatures of thousands of degrees, and a thin and high-velocity jet. Despite the difficulties, the transport and transformation behaviors of the deposition units were also researched by optical emission spectroscopy, observation of the coating microstructure and other methods. This paper reviews the progress of PS–PVD technologies considering the preparation of advanced thermal barrier coatings from the perspective of the transport and transformation behaviors of the deposition units. The development prospects of new high-performance TBCs using the PS–PVD technique are also discussed.

Formation processes and evolution of Holocene sediments in the Yangtze offshore area: A review and new interpretation on the response to sea-level rise and deltaic progradation

Seismic profiles integrated with borehole cores from offshore of the Yangtze River Delta characterize three distinctive Holocene deposition units in correspondence to estuarine, shallow marine and prodelta facies respectively (Units Ⅰ to Ⅲ). Sedimentary processes and evolution of three units in response to sea-level rise and Yangtze delta development was studied. Estuarine facies occurred as a cluster of mud ridges (unit Ⅰ) was considered to be formed during the later stage of the period ∼10-8 cal ka BP with the prevalence of tidal erosion processes. At the same time however, the area south of the ridge field experienced rapid deposition, possibly due to shelter effects of the Zhoushan Archipelago. Unit Ⅱ, characterized by homogeneous mud composition, rapid accumulation rates and a seaward dipping structure, indicated a gravity flow deposition most likely related to the wave and/or tidal current induced fluid mudflows during the period of ∼ 8-5 cal ka BP. Intrusion of a mud diapir during ∼5-3 cal ka BP related to gravity subsidence localized near the river mouth, lead to deformation of unit Ⅱ. During the ∼3 ka to present, the delta advanced to the study area, depositing subaqueous clinoform (unit Ⅲ). Meanwhile, erosional processes dominated by tidal currents were promoted by the southeastward progradation of the delta. Sediments deposited in the north of the area were transformed into tidal sand ridges. We predict that the delta will likely reduce in area with a further progradation in the recent future.

Electrical switching and morphological studies on Si15Te84Cu1 thin film

The electrical switching studies of Si based ternary material with composition Si15Te84Cu1 has been presented in this paper. The material has been prepared in both bulk and thin film device form. The bulk sample is prepared by melt quenching technique. The thin film device is prepared in sandwich geometry on a glass substrate with copper as top and bottom electrodes. The material Si15Te84Cu1 is coated by flash evaporation technique and the electrodes by sputtering technique in DC mode. To carry out SET studies, electric field is employed to the device and it has been found that the thin film device exhibits memory type of switching. The essential instruments used in the fabrication of amorphous switching devices are high temperature furnace and deposition units like flash evaporation unit, sputtering unit. Keithley source-measure unit along with two probe station succoured the study of electrical switching behaviour of the device. A morphological study has been carried out with Scanning Electron Microscopy and it has revealed some structural changes, which have occurred during switching.

Radiopaque Three-dimensional Printing: A Method to Create Realistic CT Phantoms.

Purpose To develop a method to create anthropomorphic phantoms of individual patients with high precision of anatomic details and radiation attenuation properties. Materials and Methods Inkjet cartridges were filled with potassium iodide solutions (600 mg/mL) and prints were realized on plain paper (80 g/m2). Stacks of 100 prints resulted in three-dimensional phantoms of 1 cm thickness. In a first step, reproduction of patient anatomy was tested by printing computed tomographic (CT) images of a real patient abdomen scan. In a second step, gray scales, iodine deposition, and Hounsfield units were investigated by printing geometric phantoms with gray scales ranging from 0% (white) to 100% (black). On the basis of these results, a gray-scale-correction procedure was developed to achieve realistic Hounsfield units in the patient phantom. In a third step, reproduction of the real patient's Hounsfield units was verified by printing the initial patient CT scan again after application of the gray-scale-correction procedure. Data were analyzed by using Pearson correlation, linear regression, and nonlinear regression. Results The first abdomen phantom showed a detailed reproduction of the patient anatomy and demonstrated feasibility of the concept. However, individual-organ Hounsfield units deviated from the real patient CT scan. Analysis of the geometric phantoms revealed an exponential correlation between template gray scales and printer deposition. Application of a correction procedure to the template gray scales allowed for a linear correlation (r = 0.9946; 95% confidence interval: 0.9916, 0.9966). After the same correction procedure was applied to the abdomen phantom, linear correlation of phantom and patient Hounsfield units was confirmed (r = 0.9925; 95% confidence interval: 0.9635, 0.9985). Conclusion The method presented in this work can realize realistic and customizable phantoms for diagnostic and therapeutic radiology, including the reproduction of individual patients. © RSNA, 2016.

The nature, origins and distribution of ash aggregates in a large-scale wet eruption deposit: Oruanui, New Zealand

This study documents the processes and products of volcanic ash aggregation in phreatomagmatic phases of the 25.4ka Oruanui supereruption from Taupo volcano, New Zealand. Detailed textural and stratigraphic relationships of aggregates are examined in six of the ten erupted units, which range from relatively dry styles of eruption and deposition (units 2, 5) to mixed (units 6, 7, 8) and dominantly wet (unit 3). Aggregate structures and grain size distributions shift abruptly over vertical scales of cm to dm, providing diagnostic features to identify deposits emplaced primarily as vertical fallout or pyroclastic density currents (PDCs). The six categories of ash aggregates documented here are used to infer distinct volcanic and meteorological interactions in the eruption cloud related to dispersal characteristics and mode of emplacement. Our field observations support the notion of Brown et al. (2010, Origin of accretionary lapilli within ground-hugging density currents: evidence from pyroclastic couplets on Tenerife. Geol. Soc. Am. Bull. 122, 305–320) that deposits bearing matrix-supported accretionary lapilli with concentric internal structure and abundant rim fragments are associated with emplacement of PDCs. However, on the basis of grain size distributions and field relationships, it is inferred that these types of ash aggregates formed their ultrafine ash (dominantly <10μm) outer layers in the buoyant plumes of fine ash lofted from PDCs, rather than during lateral transport in ground-hugging density currents. The propagation of voluminous PDCs beneath an overriding buoyant cloud – whether coignimbrite or vent-derived in origin – is proposed to generate the observed, concentrically structured accretionary lapilli by producing multiple updrafts of convectively unstable, ash-laden air. The apparent coarsening of mean grain size with distance from source, which is observed in aggregate-bearing fall facies, reflects a combination of multi-level plume transport and enhanced proximal fallout of fine ash (<250μm) by aggregation. Gravitational fallout and melting of abundant ice in the clouds was likely to have contributed a key source of liquid water for wet aggregation in near-source areas. In contrast, deposits from relatively drier eruption phases are aggregate-poor in proximal areas, yet develop loosely-bound particle clusters and mm-scale massive ash pellets >100km from vent. It is inferred that ambient meteorological conditions play a more important role in ash fallout in these cases. Entrainment of moist air, and distal subsidence and melting of ice carried by the plume, are both likely to have contributed to the observed features of late-stage aggregation in the drier phases of eruption. These observations suggest that proximal, column-influenced aggregation processes, which weaken with distance from source, are overprinted by secondary, later-stage aggregation mechanisms farther downwind.

Nanoindentation testing on copper/diamond-like carbon bi-layer films

In the present work, the effect of indentation load on nano-mechanical properties of copper/diamond-like carbon (Cu/DLC) bi-layer films was explored. In addition, effect of Cu interlayer and influence of self bias on residual stress and various other nano-mechanical properties such as hardness ( H) and elastic modulus ( E) of Cu/DLC bi-layer films were also discussed. These Cu/DLC bi-layer films were deposited, using hybrid system involving radio frequency (RF)-plasma enhanced chemical vapor deposition and RF-sputtering units, under varied self biases from −125 to −225 V. The effect of penetration depth with varied load from 5 to 20 mN on H and E of these Cu/DLC bi-layer films was also analyzed.

Role of Sandwich Cu Layer in and Effect of Self-Bias on Nanomechanical Properties of Copper/Diamond-Like Carbon Bilayer Films

The role of sandwich Cu layer in and effect of self-bias on structural and nanomechanical properties of Cu/DLC bilayer films have been explored. Cu/DLC bilayer films were grown, under varied self-bias from−125to−225 V, using hybrid system involving radio-frequency- (RF-) plasma-enhanced chemical vapor deposition and RF-sputtering units. Surface topography and mean roughness was studied by atomic force microscope and then correlated with mechanical properties. The addition of sandwich Cu layer in DLC reduces its residual stress and does not affect bilayer film hardness and elastic modulus. Load versus displacement was also employed to estimate various other mechanical parameters, which further correlated with self-bias and structural properties. These Cu/DLC bilayer films seem to be a potential candidate for various industrial applications such as hard and protective coating on cutting tools, solar cells, and wear resistance coating on magnetic storage media.

Accounting for uncertainty in DEMs from repeat topographic surveys: improved sediment budgets

AbstractRepeat topographic surveys are increasingly becoming more affordable, and possible at higher spatial resolutions and over greater spatial extents. Digital elevation models (DEMs) built from such surveys can be used to produce DEM of Difference (DoD) maps and estimate the net change in storage terms for morphological sediment budgets. While these products are extremely useful for monitoring and geomorphic interpretation, data and model uncertainties render them prone to misinterpretation. Two new methods are presented, which allow for more robust and spatially variable estimation of DEM uncertainties and propagate these forward to evaluate the consequences for estimates of geomorphic change. The first relies on a fuzzy inference system to estimate the spatial variability of elevation uncertainty in individual DEMs while the second approach modifies this estimate on the basis of the spatial coherence of erosion and deposition units. Both techniques allow for probabilistic representation of uncertainty on a cell‐by‐cell basis and thresholding of the sediment budget at a user‐specified confidence interval. The application of these new techniques is illustrated with 5 years of high resolution survey data from a 1 km long braided reach of the River Feshie in the Highlands of Scotland. The reach was found to be consistently degradational, with between 570 and 1970 m3 of net erosion per annum, despite the fact that spatially, deposition covered more surface area than erosion. In the two wetter periods with extensive braid‐plain inundation, the uncertainty analysis thresholded at a 95% confidence interval resulted in a larger percentage (57% for 2004–2005 and 59% for 2006–2007) of volumetric change being excluded from the budget than the drier years (24% for 2003–2004 and 31% for 2005–2006). For these data, the new uncertainty analysis is generally more conservative volumetrically than a standard spatially‐uniform minimum level of detection analysis, but also produces more plausible and physically meaningful results. The tools are packaged in a wizard‐driven Matlab software application available for download with this paper, and can be calibrated and extended for application to any topographic point cloud (x,y,z). Copyright © 2009 John Wiley &amp; Sons, Ltd.

Neogene–Recent extension on the eastern flank of Mount Olympus, Greece

The Olympus massif of NE Greece comprises metamorphosed and deformed Triassic and Cretaceous–Eocene carbonates considered to represent part of the passive southwestern margin of Neotethys, which separated the Apulia plate of mainland Greece from southern Europe in the Mesozoic. Ocean closure in the Early Tertiary led to subduction of this passive margin, as a result of which the Olympus carbonates were tectonically overridden in the Eocene by a series of thrust sheets consisting of locally high P/T (blueschist) metamorphosed continental margin sediments, basement granitoid gneisses, and ophiolitic rocks. Following collision, uplift of the Olympus carbonates by ~ 6–8 km was accomplished by Early Neogene ductile and Late Neogene–Recent brittle normal faulting, which exposed the carbonates in the form of a structural window through the overriding thrust stack. The focus of this exhumation occurred on the eastern flank of the massif where a thick calc–mylonite with down-to-the-east sense-of-shear indicators and a prominent zone of NNW- to NW-trending brittle normal faults separate the carbonates from telescoped structurally overlying units. Published 40Ar/ 39Ar microcline ages that indicate a thermal perturbation close to the contact zone in excess of 100–150 °C at 16–23 Ma (Early Miocene) are taken to date the onset of ductile extension, and imply long-term uplift rates of ~ 0.4 to 1 km/m.y. Degradation of Pleistocene glacial features on the Olympus massif and the presence on its eastern piedmont of deeply incised streams, erosional terraces, and fault scarps that offset the sedimentary deposits of three cycles of Pleistocene glacial deposition (Units 1–3), testify to its continuing uplift. A prominent frontal fault offsets Unit 2 by > 150 m and several subsidiary NW-trending normal faults with a cumulative displacement of ~ 130 m offset a paleosol developed on Unit 1. Kinematic indicators indicate normal dip-slip movement. Cumulative fault displacement for Unit 1 exceeds 277 m, yielding a minimum uplift rate of ~ 1.3 mm/yr, given the oxygen isotope stage 7 (Mindel/Riss) age of 210 ka proposed for the Unit 1 paleosol. Cumulative offset of > 196 m for the paleosol developed on Unit 2 yields an uplift rate of ~ 1.6 mm/yr, given its proposed isotope stage 5e (Riss/Würm) age of 125 ka. This estimate is supported by longitudinal valley profile data that document ~ 200 m of stream incision since Unit 2 deposition and show the offset as reflecting uplift of the Olympus massif rather than subsidence of the adjacent Gulf of Thermaikos. Assuming 1.8 Ma for the base of the Pleistocene, these rates yield a total uplift range for the Quaternary of 2.3–4.1 km, consistent with the present 2.6 km height of Olympus above the exposed frontal fault. Neogene uplift of Olympus was likely facilitated by extension accompanying the opening of the Aegean back-arc basin during the Miocene as a result of the southward retreat of the Hellenic subduction zone. For the Pliocene–Recent, uplift was likely facilitated by extension linked to the termination of dextral motion at the western end of the North Anatolian Fault associated with the westward tectonic escape of Anatolia .

Geologic framework of the 2005 Keathley Canyon gas hydrate research well, northern Gulf of Mexico

The Keathley Canyon sites drilled in 2005 by the Chevron Joint Industry Project are located along the southeastern edge of an intraslope minibasin (Casey basin) in the northern Gulf of Mexico at 1335 m water depth. Around the drill sites, a grid of 2D high-resolution multichannel seismic data designed to image depths down to at least 1000 m sub-bottom reveals 7 unconformities and disconformities that, with the seafloor, bound 7 identifiable seismic stratigraphic units. A major disconformity in the middle of the units stands out for its angular baselapping geometry. From these data, three episodes of sedimentary deposition and deformation are inferred. The oldest episode consists of fine-grained muds deposited during a period of relative stability in the basin (units e, f, and g). Both the BSR and inferred gas hydrate occur within these older units. The gas hydrate occurs in near-vertical fractures. A second episode (units c and d) involved large vertical displacements associated with infilling and ponding of sediment. This second interval corresponds to deposition of intercalated fine and coarse-grained material that was recovered in the drill hole that penetrated the thin edges of the regionally much thicker units. The final episode of deposition (units a and b) occurred during more subdued vertical motions. Hemipelagic drape (unit a) characterizes the modern seafloor. The present-day Casey basin is mostly filled. Its sill is part of a subsiding graben structure that is only 10–20 m shallower than the deepest point in the basin, indicating that gravity-driven transport would mostly bypass the basin. Contemporary faulting along the basin margins has selectively reactivated an older group of faults. The intercalated sand and mud deposits of units c and d are tentatively correlated with Late Pleistocene deposition derived from the western shelf-edge delta/depocenter of the Mississippi River, which was probably most active from 320 ka to 70 ka [Winker, C.D., Booth, J., 2000. Sedimentary dynamics of the salt-dominated continental slope, Gulf of Mexico: integration of observations from the seafloor, near-surface, and deep subsurface. In: Proceedings of the GCSSEPM Foundation 20th Annual Research Conference, Deep-water Reservoirs of the World, pp. 1059–1086]. The presence of sand within the gas hydrate stability zone (in units c and d) is not sufficient to concentrate gas hydrate even though dispersed gas hydrate occurs deeper in the fractured mud/clay-rich sections of units e and f.

Late Quaternary depositional history of the Reuss delta, Switzerland: constraints from high‐resolution seismic reflection and georadar surveys

AbstractGlacial erosion has caused overdeepening of many alpine valleys. After retreat of the ice, they were filled with heterogeneous deposits of glacial, lacustrine and fluvial sediments. A typical example of such a valley segment and its infill is the Reuss delta on the southern shore of Lake Lucerne in Switzerland. To obtain a detailed three‐dimensional image of this valley segment, the ETH Institute of Geophysics has acquired several two‐dimensional, high‐resolution seismic and georadar profiles, and conducted a three‐dimensional georadar survey. Interpretations of these geophysical data were constrained by a geological core extracted from a borehole 300 m deep near the investigation site. The seismic profiles imaged ca. 600 m of sediment infill above bedrock. Based on their reflection characteristics, five different deposition units were distinguished. These units were interpreted as a succession of clay/silt at the base, followed by different sand units with variable but generally increasing amounts of gravel. This succession represented a prograding delta that filled the southern part of Lake Lucerne. The latest fluvial development of the region is best represented by the georadar data. In particular, the three‐dimensional georadar data set provides a detailed view of an ancient braided river channel Copyright © 2002 John Wiley &amp; Sons, Ltd.

A model for the evaluation of long-term airborne pollution transport at regional and continental scales

The paper contains the description of numerical model of the airborne pollution transport developed by a scientific team of M. Galperin. During several years the model was used for the calculations in Meteorological Synthesizing Centre – East, within the scope of Co-operational Programme for Monitoring and Evaluation of the Long-Range Transmission of air Pollutants in Europe (EMEP). The paper presents the extensive description of the current version of the model and outlines the results of its quality assurance. The model is based on an original Eulerian advection scheme with variable time step, which can be classified as a “pseudo-Lagrangian” scheme. Vertical concentration profiles are parameterized by truncated Gaussian function with dynamic parameters calculated at every model time step. The model includes two types of chemistry and deposition units: acid compounds and ammonia, and heavy metals carried with aerosol particles. One of the model advantages is the ability to make the evaluation of source–receptor pollution exchange for substances with non-linear atmospheric chemistry and deposition. The model evaluation was carried out by the comparison of multi-annual calculated concentrations with measured values for several acidifying substances.

Properties of sputtered hard coatings depending on macro- and micro-geometry of the substrates

The deposition of hard coatings on tools and machine components is a well-known technique to produce wear resistant surfaces in many cases. In many cases, lots of small tools and machine parts are deposited in large deposition units in one batch by the use of substrate manipulation. In addition, components with large surfaces need special manipulation. This investigation points out how the choice of substrate influences the coating properties in a given deposition process. Aspects of material, geometry and kinematics are studied in addition to the known levels of influence, such as deposition technology, equipment and deposition parameters. Not only macro-geometry, but also micro-geometry determine the quality of a coating. Specimens of different size, shape and roughness were coated and analysed to provide a contribution towards a better understanding that the same deposition processes may produce coatings with different properties depending on the objects to be coated. As a result, a general model for substrate influences on coating properties is proposed. This model takes into account the important substrate aspects for deposition of thin films on mechanical components in tribology with vacuum technologies. This information is necessary when changing the nature or number of objects to be coated in a given deposition unit, especially for different machine parts instead of small tools.

Wear of Co-Ni thin film magnetic recording tape against metallic and ceramic surfaces

The unlubricated friction and wear of Co-20 wt.% Ni thin film magnetic recording tape are shown to be strongly dependent on the nature of the counterface. Stainless steel, ferrite and plain carbon steel give relatively high wear rates of the film whereas alumina and chromium provide the least wear. The friction and wear of the film is also substantially influenced by the orientation of its columnar grain boundaries, the wear rate being lower with the grain than against the grain direction for all the counterface materials tested. The application of the results to the design and operation of video recorders and deposition units is discussed.

Apparatus for Ultrahigh-Vacuum In Situ Thin-Film Studies

First Page

Stratigraphy and Seriation

AbstractStratigraphic interpretation rests on two principles: the principle of superposition and the principle that deposition units can be identified by cultural content. The sequence of deposition units derived from a case of superposition may not give a true cultural sequence if mixing, filling, or collecting has affected the cultural contents of the units. There are two kinds of seriation: evolutionary seriation, done on the basis of an assumed general law of cultural development, and similary seriation, done on the basis of similarities and differences in objects or deposition units compared. Similiary seriation assumes only that cultural change is normally gradual. Of the two kinds of seriation, only similiary seriation can give credible results. Some evidence of archaeological associations is necessary to control the possibility of non-gradual change resulting from sudden outside influence or archaism. If the conditions for success can be met, either stratigraphy or seriation can provide a credible sequence. Each method provides a check on the other; the most credible results are achieved by combining the two.