Numerous chondritic impactors and oxidized magma ocean set Earth’s volatile depletion

Earth’s surface environment is largely influenced by its budget of major volatile elements: carbon (C), nitrogen (N), and hydrogen (H). Although the volatiles on Earth are thought to have been delivered by chondritic materials, the elemental composition of the bulk silicate Earth (BSE) shows depletion in the order of N, C, and H. Previous studies have concluded that non-chondritic materials are needed for this depletion pattern. Here, we model the evolution of the volatile abundances in the atmosphere, oceans, crust, mantle, and core through the accretion history by considering elemental partitioning and impact erosion. We show that the BSE depletion pattern can be reproduced from continuous accretion of chondritic bodies by the partitioning of C into the core and H storage in the magma ocean in the main accretion stage and atmospheric erosion of N in the late accretion stage. This scenario requires a relatively oxidized magma ocean ($$\log _{10} f_{{\mathrm{O}}_2}$$ log 10 f O 2 $$\gtrsim$$ ≳ $${\mathrm{IW}}$$ IW $$-2$$ - 2 , where $$f_{{\mathrm{O}}_2}$$ f O 2 is the oxygen fugacity, $$\mathrm{IW}$$ IW is $$\log _{10} f_{{\mathrm{O}}_2}^{\mathrm{IW}}$$ log 10 f O 2 IW , and $$f_{{\mathrm{O}}_2}^{\mathrm{IW}}$$ f O 2 IW is $$f_{{\mathrm{O}}_2}$$ f O 2 at the iron-wüstite buffer), the dominance of small impactors in the late accretion, and the storage of H and C in oceanic water and carbonate rocks in the late accretion stage, all of which are naturally expected from the formation of an Earth-sized planet in the habitable zone.

The Effect of Sandblasting on Properties and Structures of the DC03/1.0347, DC04/1.0338, DC05/1.0312, and DD14/1.0389 Steels for Deep Drawing

The erosion phenomenon has a significant influence on many metallic materials used in numerous industrial sectors. In this paper, we present the results of an analysis of the influence of abrasive impact erosion on surface and properties of DC03/1.0347, DC04/1.0338, DC05/1.0312, and DD14/1.0389 deep drawing steels. The chemical composition, static tensile tests, hardness tests, drawability tests, erosion tests, microstructure analysis, surface roughness, and hardness of the plates were investigated. The wear mechanisms and wear behavior of the investigated steels were also discussed. The results obtained in this study allowed the assessment of the microstructural changes in deep drawing steels under the influence of intense erosive impact. The obtained results indicate that the erosive impact may cause a significant grain refinement of the microstructure of the surfaces of the investigated materials. Moreover, large amounts of heat released during erosive impact may cause the material phase changes. This research expands the knowledge on specific mechanisms taking place during sandblasting and their influence on the properties of deep drawing steels and their wear behavior.

Nonconventional Machining and Materials Processing: Proposed Design for Abrasive Jet Machining (AJM)

High degree Abrasive Jet (AJ) is applied in Abrasive Jet Machining (AJM) as a process that is based of Machine-driven Energy (MDE). The abrasives are applied in the removal of resources from work surfaces based on impact erosion. AJ is generated through the acceleration of very fine abrasive particles in considerably gas that has been pressurizes i.e. carrier gas. In this case, jets are utilized to transform this pressurized energy into kinetic energy, which is also directs jets to the work surfaces at an impingement angle. During the impact, rigid abrasive particles are used to slowly remove resources through erosion and with the assistance of brittle fracture. This paper evaluates and recommends a design for AJM. The various components have also been chosen after the relevant design assessment procedures have been done. The AJM model has been design with reference to the present components.

Numerical assessment of the vulnerability to impact erosion of a pump as turbine in a water supply system

Nowadays, the installation of pumps as turbines (PATs) in water supply systems (WSSs) is considered attractive because it is able to effectively combine the pressure regulation with the small-scale hydropower generation. One critical aspect concerns the behaviour of the PAT in the presence of solid particles in the flow which impinge against the inner surface of the device, producing a loss of material termed impact erosion. In this paper, the numerical assessment of PAT erosion is performed, by referring, as a case study, to an existing pressure control station in Southern Italy. The variable operative strategy (VOS) was applied to derive the frequency distribution of flow rates over the PAT operation, under the hypothesis of performing the hydraulic regulation of the hydropower plant. The commercial computational fluid dynamics (CFD) code Ansys Fluent was employed for simulating the liquid–solid flow inside the PAT and then coupled with an in-house code to estimate the erosion. The vulnerability of the PAT to wear was analysed by varying its flow rate, aiming at characterizing the decay of PAT components at a constant rotational speed. Finally, a detailed characterization of the PAT response to the particle impingement at its best efficiency point (BEP) was developed and discussed.