Qualitative Analysis of Magnetic Moment in BaxTiO3 - Ni xFe3- xO4 Nanocomposite Synthesized by Novel low Temperature Technique

A novel low temperature preparation technique (<500ºC) is employed for synthesizing nanoscale Barium Titanate -Nickel ferrite composites, where the particle size is controllable. Two different ratios of hard and soft site composites (BTO-NFO 80:20, BTO-NFO 70:30) are synthesized and characterized to study their unique structural, morphological and magnetic properties. The structural refinement studies using XRD data showed 43 % of hard phase (anorthic structure) and 57% of soft phase (Cubic Structure) for BTO-NFO 80:20 and similarly 76% of hard phase and 24% of soft phase in the BTO-NFO 70:30 composite respectively. The SEM and EDAX are used to identify smaller particles of 10 nm using histogram and their sample purity. The VSM analysis at room temperature shows superparamagnetic behavior within the soft ferro magnet with maximum retentivity 2.39 emu/g and saturation magnetization, 10.71 emu/g stating that the composites can be used for various biological applications like drug delivery, hyperthermia, MRI, etc. The ratio Mr/Ms is much less than 0.5, which states that multidomain grains or single domains are formed and the particle interaction is by magneto-static interaction confirming its superparamagnetic nature.

Geometric Influence of Hard Phase on Corrosion Performance between WC-Reinforced Coatings Prepared by High-Velocity Oxygen-Fuel Spray and Electric Contact Strengthening

Several kinds of WC-reinforced coatings were prepared by high-velocity oxygen-fuel spray (HVOF) and electric contact strengthening (ECS), respectively, and their corrosion behaviors in 3.5% NaCl solution were investigated. The microstructure, element distribution, phase and corrosion resistance of these coatings were compared. The results showed that, compared with HVOF-sprayed coatings, the ECS-prepared coatings were denser and with lower porosity. Simultaneously, the ECS coatings that used raw powder commercial WC-12Co retained the original spherical geometry of the hard phase. In open-circuit potential measurements, these ECS coatings gave higher stable potentials (Eocp). In potentiodynamic polarization tests, although the corrosion currents (icorr) of the homogeneous coatings were approximately the same, these ECS coatings still exhibited higher corrosion potentials (Ecorr). The spherical geometric distribution of the hard phase led to a bounded diffusion model caused by the diffusion change of corrosion products.

Microstructure and Abrasive Wear Resistance of Metal Matrix Composite Coatings Deposited on Steel Grade AISI 4715 by Powder Plasma Transferred Arc Welding Part 2. Mechanical and Structural Properties of a Nickel-Based Alloy Surface Layer Reinforced with Particles of Tungsten Carbide and Synthetic Metal–Diamond Composite

The article is the continuation of a cycle of works published in a Special Issue of MDPI entitled “Innovative Technologies and Materials for the Production of Mechanical, Thermal and Corrosion Wear-Resistant Surface Layers and Coatings” related to tests concerning the microstructure and mechanical properties of innovative surface layers made using the Powder Plasma Transferred Arc Welding (PPTAW) method and intended for work surfaces of drilling tools and machinery applied in the extraction industry. A layer subjected to tests was a metal matrix composite, made using powder based on a nickel alloy containing spherical fused tungsten carbide (SFTC) particles, which are fused tungsten carbide (FTC) particles and spherical particles of tungsten-coated synthetic metal–diamond composite (PD-W). The layer was deposited on the substrate of low-alloy structural steel grade AISI 4715. The results showed that the chemical composition of the metallic powder as well as the content of the hard phase constituting the matrix enabled the making of a powder filler material characterised by very good weldability and appropriate melting. It was also found that the structure of the Ni-WC-PD-W layer was complex and that proper claddings (characterised by the uniform distribution of tungsten carbide (WC)) were formed in relation to specific cladding process parameters. In addition, the structure of the composite layer revealed the partial thermal and structural decomposition of tungsten carbide, while the particles of the synthetic metal–diamond composite remained coherent. The deposited surface layer was characterised by favourable resistance to moderate dynamic impact loads with a potential energy of 200 J, yet at the same time, by over 12 times lower metal–mineral abrasive wear resistance than the previously tested surface layer made of cobalt-based composite powder, the matrix of which contained the hard phase composed of TiC particles and synthetic metal–diamond composite. The lower abrasive wear resistance could result from a different mechanism responsible for the hardening of the spherical particles of the hard phase susceptible to separation from the metal matrix, as well as from a different mechanism of tribological wear.

Toughening Mechanism of Unidirectional Stretchable Composite

Composite materials have been long developed to improve the mechanical properties such as strength and toughness. Most composites are non-stretchable which hinders the applications in soft robotics. Recent papers have reported a new design of unidirectional soft composite with superior stretchability and toughness. This paper presents an analytical model to study the toughening mechanism of such composite. We use the Gent model to characterize the large deformation of the hard phase and soft phase of the composite. We analyze how the stress transfer between phases deconcentrates the stress at the crack tip and enhances the toughness. We identify two types of failure modes: rupture of hard phase and interfacial debonding. We calculate the average toughness of the composite with different physical and geometric parameters. The experimental results in literature agree with our theoretical predictions very well.

CHILD SEXUAL ABUSE IN INDIA

Today, every child in this world has to undergo a hard phase in his/her life. The hard phase could be in the form of physical or mental harassment. These cruel acts, done by some grown-up men and women will have a huge impact on the future generation. One such act is Child Sexual Abuse (CSA). Its prevalence is perceptible all over the world. This research article gives exclusive importance to CSA in India. A general understanding of CSA in the public eye is coitus. However, the reality is touching or speaking with the intention of abusing the child either physically or emotionally itself is a CSA. The statistics and case studies referred to in this article have their source from the leading national and international newspapers. The post-traumatic phase or the consequences of CSA has been dealt with in detail. This article can also serve as an eye-opener by making the readers aware of the rules and regulations available at the state, national, and international level for the welfare of children. The present article also throws light on the prevention of CSA and tailored guidelines for handling victims of CSA. This article could also be used by future researchers in exploring the various factors behind CSA and policymakers, in understanding the status quo and strengthening the system accordingly. It can also serve as an eye-opener for the common public to understand the nuances involved in protecting a child against sexual advancements.

Surface Modification of Ti-6Al-4V by Gas-liquid Mixed EDM

Ti-6Al-4V alloy is widely used in many fields due to its excellent properties. However, its further applications is limited by its low hardness and poor wear resistance. In this paper, gas-liquid mixed electrical discharge machining (EDM) process was applied for surface modification of Ti-6Al-4V alloy. The multi-hole electrode was adopted to flow nitrogen to mix nitrogen with special spark oil. The effect of different parameters (peak current and pulse duration) on surface morphology, cross section morphology, micro hardness and wear resistance were investigated. The results indicated that the gas-liquid mixed EDM process has better performance on sample surface with fewer pores and shallow craters. A continuous and thick recast layer was obtained by gas-liquid mixed EDM process and N element was migrated to the sample surface from nitrogen gas. The XRD results demonstrated that TiN hard phase was formed on the sample surface, thus the micro hardness was nearly three times higher than that of the matrix, reaching 1329.5HV, and the wear resistance is improved accordingly. The surface of Ti-6Al-4V alloy was modified by gas-liquid mixed EDM process.

Porous granules formation from oil crops by extrusion process: a theoretical perspective

The introduction of extruders, in particular how it works and its principles, must be started from the definition of the extrusion process, the description of its development and types, as well as its functions and advantages. In order to understand the process of extrusion technology, it is necessary to go into detailed descriptions and discussions together with theoretical insights of the subject. In the present article, we discuss a theoretical perspective of production of porous granules from oil crops by extrusion technology. Let’s divide this theoretical perspective into three steps. At first, we study the modeling of statics of oil crop mix compressibility together with carbon dioxide. At second, we study the heat exchange and phase transformation during the stroke of oil crop extruder filled with CO2. At third, we observe the deformation of the oil crops during the extrusion process. There is a probability that extrusion process of oil crop mix with the hard phase of carbon dioxide provides technological way that does not overheat the cellular structure. Potentially, the equation of Van der Waals is able to describe the change in volume of oil crops, which may be related with range of factors associated with volume expansion, calculated by equations as the expansion of granule material takes place at the outlet of extruder matrix. The extrusion processing of a mix of oil crops and carbon dioxide in hard phase at initial stage may likely occur as temperature declines. The resulting values show good compliance of theoretical results to experimental data on the example of coriander seeds.

Hardness characteristics of as-cast Ni-Ru-Zr alloys

The Vickers hardnesses of 21 as-cast Ni-Ru-Zr alloys of different compositions were studied, and nanohardness indentations were done on the individual phases. The results were used to explain the brittleness by assessing the proportions of the phases, and their morphologies. The compound hardnesses varied between 704 - 1289 HV, with ~ZrRu2 being the hardest phase, and ~Zr2Ni7 being the least hard phase. The sample hardnesses were 300 - 1015 HV. Most of the samples were brittle, although there were regions of toughness around Ni36:Ru13:Zr51 and Ni20:Ru5:Zr75 (at.%). No alloy was identified to have potential good mechanical properties.

Estratégias para o Desenvolvimento de Revestimentos Resistentes ao Desgaste: Uma Revisão

This review presents the possible strategies to increase the wear resistance of hardfacing alloys based on metallic matrix and second hard phase’s coupled design. As the wear resistance is not an intrinsic property of material, the results of many wear tests are discussed in light of the interaction between mechanical properties and wear severity, which is dependent on the microstructure. These strategies are based on the hardness increase, considering the kind and size of the second hard phase, the fracture toughness, and the dilution level of hardfacing. The guidelines provided for designing better the hardfacing alloys for usual abrasion conditions depending on the volume fraction of the second hard phase.