Experimental investigation of effect of printing direction and surface roughness on the mechanical properties of AlSi10Mg-alloy produced by selective laser melting

The additive manufacturing has initially gained popularity for production of non-loadbearing parts and components or in the fields where the material strength and ductility are less important such as modelling and rapid prototyping. But as the technology develops, availability of metal additive manufacturing naturally dictates the desire to use the produced components in load-bearing parts. This requires not-only a thorough documentation on the mechanical properties but also additional and independent research to learn the expected level of variation of the mechanical properties and what factors affect them. The presented paper investigates strength, ductility, hardness, and microstructure …

Preparation and Characterization of Spherical Nickel Silicide Powder by Inductively Coupled Plasma Spheroidization for Additive Manufacturing

Author's accepted manuscript Metal alloy powder with spherical-shaped morphology, high flowability, and packing density is the main requirements for metal-based additive manufacturing (AM). Among metal alloys, nickel silicide is considered as a potential candidate due to its unique properties such as high melting point, good electrical conductivity, as well as high corrosion and wear resistance. However, the fabrication of spherical nickel silicide powder has proven to be a challenging task. In the present work, spherical NiSi16 alloy powders were synthesized by inductively coupled plasma spheroidization (ICPS). The influence of the feed rate on the properties of the as-prepared powder was …

On the Influence of Cross-Section Size on Measured Strength of SLM-Produced AlSi10Mg-Alloy

The freedom in choice of geometries in additive manufacturing (AM) favors the use of structures with large surface and small cross-section such as lattice structures and thin-walled hollow profiles. On the other hand, the practices of strength testing of metals require a certain bulk of the material to be printed to be able to produce a sample and test material properties. The size of the sample cross section might influence the strength and up to 30% decrease in strength for small struts was reported in the literature. Understanding the influence of the cross-section size on the strength of SLM-produced metal is crucial to be able to relate the strength determined through tensile testing a…

High temperature oxidation of higher manganese silicides

Abstract The oxidation kinetics and mechanisms of higher manganese silicides (HMS) MnSi1.75, MnSi (1.75-x)Gex, MnSi(1.75-x)Alx (with x = 0.005 and 0.01)were studied and the effects of densification methods and dopant concentration discussed. Oxidation experiments were conducted using thermogravimetry (TGA), while post characterization with X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscope (SEM) showed that spark plasma sintering (SPS) is a better densification method than hot pressing (HP). Except for undoped HMS, HMS doped with 0.5at% Ge had the lowest oxidation rate. Stable formation of a SiO2 protective layer was the main reason for improved oxidation resistance in …

Characterization and Evaluation of Hydrothermal Liquefaction Char from Alkali Lignin in Subcritical Temperatures.

An evaluation of hydrothermal liquefaction (HTL) char is investigated in this work. Morphological studies, N2 adsorption behavior, FTIR analysis, thermal behavior, and elemental composition are studied. The HTL char yield showed an increase with higher operating temperatures. It increased from 11.02% to 33% when the temperature increased from 573 K to 623 K. At lower temperatures, the residence time showed an impact on the yield, while close to the critical point, residence time became less impactful. Elemental analysis showed that both higher operating temperatures and longer residence times increased the nitrogen content of the chars from 0.32% to 0.51%. FTIR analysis suggested the char b…

Highly efficient maximum power point tracking control technique for PV system under dynamic operating conditions

A novel meta-heuristic optimization algorithm based MPPT control technique for PV systems under complex partial shading condition

Abstract The need to combat the increase in global warming is well taken by solar energy lead renewable energy resources. The techno-economic feasibility of solar systems in the form of photovoltaic (PV) generation is highly dependent upon its operating conditions. The nonlinear control problem is further worsened by partial shading (PS) environment causing major power losses. Bio-inspired maximum power point tracking (MPPT) control techniques, in literature, exhibit some major common drawbacks such as high tracking and settling time, oscillations at global maxima (GM), and local maxima (LM) trapping under PS conditions. This paper presents a novel search and rescue (SRA) optimization algor…

Graphene and graphene oxide on Ir(111) are transparent to wetting but not to icing

Anti-icing coatings reduce the freezing onset temperature for water by changing the chemical and physical environment at the water-substrate interface to prevent ice nucleation and growth. Graphene oxide has several attributes that make it attractive as an anti-icing coating and it has been theoretically predicted that graphene oxide has a lower freezing onset temperature than pristine graphene. Here, we test this hypothesis using carefully prepared, well-characterized graphene oxide substrates. We compare the water contact angle for graphene and graphene oxide coatings, both prepared on iridium(111) surfaces. The results show both materials to be transparent to wetting, but indicate a lowe…

The effect of Mo and Ge reactive elements on high-temperature oxidation of higher manganese silicide

Abstract Higher manganese silicide (HMS) alloys (Mnx-αMoαSiy-βGeβ (x = 0.99–1.011, α = 0.005–0.02, y = 1.75, β = 0.005–0.01)) were studied to elucidate the effect of Mo and Ge pertaining to oxidation. Oxidation experiments were conducted using thermogravimetry and characterized using x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Isoconversion experiments below 450 °C, shows that doping (up to 2 at%) raises the oxidation potential of HMS. Isothermally, the oxidation rate reduces buy one order of magnitude by doping on Mn and/or Si sites from 0.5 to 2 at%, revealing that the dopants-based oxides do not lessen the robustness of SiO2 oxide.

Training Deep Neural Networks with Novel Metaheuristic Algorithms for Fatigue Crack Growth Prediction in Aluminum Aircraft Alloys

Fatigue cracks are a major defect in metal alloys, and specifically, their study poses defect evaluation challenges in aluminum aircraft alloys. Existing inline inspection tools exhibit measurement uncertainties. The physical-based methods for crack growth prediction utilize stress analysis models and the crack growth model governed by Paris’ law. These models, when utilized for long-term crack growth prediction, yield sub-optimum solutions and pose several technical limitations to the prediction problems. The metaheuristic optimization algorithms in this study have been conducted in accordance with neural networks to accurately forecast the crack growth rates in aluminum alloys. Through ex…