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.

Multiblock Elastomers TPEAA and TPEEA: Physical Structure and Properties

A three series of terpolymers composed of the blocks PTMO (MPTMO = 1000 g/mol) or DLAol (MDLAol = 540 g/mol), PA12 (MPA12 = 2000 g/mol) and xGT (DPxGT = 2) with various chemical compositions of ester block were obtained. The series differ in the chemical structure of the flexible block and weight content of the soft phase. The effect of the number of carbons dividing the terephthalate groups on the synthesis, structure and properties of these elastomers has been investigated. To confirm assumed chemical structure Carbon-13 (13C NMR) and Proton (1H NMR) Nuclear Magnetic Resonance and Fourier-transform Infrared Spectroscopy (FT-IR) were used. The influence of chemical compositions of ester block on the thermal properties and the phase separation of obtained systems were defined by Differential Scanning Calorimetry (DSC), Dynamic Mechanical Thermal Analysis (DMTA) and Wide Angle X-ray Scattering (WAXS). The mechanical and elastic properties were evaluated.

Phase-locked constructing dynamic supramolecular ionic conductive elastomers with superior toughness, autonomous self-healing and recyclability

Stretchable ionic conductors are considerable to be the most attractive candidate for next-generation flexible ionotronic devices. Nevertheless, high ionic conductivity, excellent mechanical properties, good self-healing capacity and recyclability are necessary but can be rarely satisfied in one material. Herein, we demonstrate a novel ionic conductor design, dynamic supramolecular ionic conductive elastomers (DSICE), via “phase-locked” strategy, wherein “locking soft phase” polyether backbone conducts lithium-ion (Li+) transport and the combination of dynamic disulfide metathesis and stronger supramolecular quadruple hydrogen bonds in the hard domains contributes to the self-healing capacity and mechanical versatility. The dual-phase design performs its own functions and the conflict among ionic conductivity, self-healing capability, and mechanical compatibility can be thus defeated. The well-designed DSICE exhibits high ionic conductivity (3.77×10−3 S m−1 at 30°C), high transparency (92.3%), superior stretchability (2615.17% elongation), strength (27.83 MPa) and toughness (164.36 MJ m−3), excellent self-healing capability (~99% at room temperature) and favorable recyclability. This work provides a new strategy for designing the advanced ionic conductors and offers promise for flexible iontronic devices or solid-state batteries.

Characterization of variable-sensitivity force sensor using stiffness change of shape-memory polymer based on temperature

In the present study, we propose a variable-sensitivity force sensor using a shape-memory polymer (SMP), the stiffness of which varies according to the temperature. Since the measurement range and sensitivity can be changed, it is not necessary to replace the force sensor to match the measurement target. Shape-memory polymers are often described as two-phase structures comprising a lower-temperature “glassy” hard phase and a higher-temperature “rubbery” soft phase. The relationship between the applied force and the deformation of the SMP changes depending on the temperature. The proposed sensor consists of strain gauges bonded to an SMP bending beam and senses the applied force by measuring the strain. Therefore, the force measurement range and the sensitivity can be changed according to the temperature. In our previous study, we found that a sensor with one strain gauge and a steel plate had a small error and a large sensitivity range. Therefore, in the present study, we miniaturize this type of sensor. Moreover, in order to describe the viscoelastic behavior more accurately, we propose a transfer function using a generalized Maxwell model. We verify the proposed model experimentally and estimated the parameters by system identification. In addition, we realize miniaturization of the sensor and achieve the same performance as in our previous study. It is shown that the proposed transfer function can capture the viscoelastic behavior of the proposed SMP sensor quite well.

Assessment of the Hardening Behavior and Tensile Properties of a Cold-Rolled Bainitic–Ferritic Steel

The automotive field is continuously researching safer, high-strength, ductile materials. Nowadays, dual-phase (DP) steels are gaining importance, since they meet all these requirements. Dual-phase steel made of ferrite and bainite is the object of a complete microstructural and mechanical characterization, which includes tensile and bending tests. This specific steel contains ferrite and bainite in equal parts; ferrite is the soft phase while bainite acts as a dispersed reinforcing system. This peculiar microstructure, together with fine dispersed carbides, an extremely low carbon content (0.09 wt %), and a minimal degree of strain hardening (less than 10%) allow this steel to compete with traditional medium-carbon single-phase steels. In this work, a full pearlitic C67 steel containing 0.67% carbon was used as a benchmark to build a comparative study between the DP and SP steels. Moreover, the Crussard–Jaoul (C-J) and Voce analysis were adopted to describe the hardening behavior of the two materials. Using the C-J analysis, it is possible to separately analyze the ferrite and bainite strain hardening and understand which alterations occur to DP steel after being cold rolled. On the other hand, the Voce equation was used to evaluate the dislocation density evolution as a function of the material state.

The Effects of Forming CeFe2 on Phase Structure and Magnetic Properties in Ce-Rich Nd-Ce-Fe-B Permanent Magnetic Materials

The decomposition of the Nd-Ce-Fe-B phase to form CeFe2 has been usually believed to have an important positive effect on the magnetic properties of Nd-Ce-Fe-B permanent magnetic materials. In this work, a new decomposition process of the Nd-Ce-Fe-B phase on the formation of the CeFe2 phase was observed to play a negative role in its magnetic properties. It is demonstrated that the Nd-Ce-Fe-B phase decomposes into non-magnetic CeFe2, accompanied by the precipitation of Fe soft-phase. The kinks usually occurring in the demagnetization curves of Ce-rich Nd-Ce-Fe-B magnets have been determined to be related to the Fe soft-phase. Instead of using CeFe2 as a grain-boundary phase, another Ce-Cu boundary phase has been explored to efficiently improve the coercivity of Ce-rich Nd-Ce-Fe-B magnets, provided that the Ce-Cu boundary phase has an appropriate Ce to Cu ratio. The present results contribute to the mechanism comprehension and high-performance design of Nd-Ce-Fe-B permanent magnetic materials.

Effect of Bainite to Ferrite Yield Strength Ratio on the Deformability of Mesostructures for Ferrite/Bainite Dual-Phase Steels

The strength and plasticity balance of F/B dual-phase X80 pipeline steels strongly depends on deformation compatibility between the soft phase of ferrite and the hard phase of bainite; thus, the tensile strength of ferrite and bainite, as non-negligible factors affecting the deformation compatibility, should be considered first. In this purely theoretical paper, an abstract representative volume elements (RVE) model was developed, based on the mesostructure of an F/B dual-phase X80 pipeline steel. The effect of the yield strength difference between bainite and ferrite on tensile properties and the strain hardening behaviors of the mesostructure was studied. The results show that deformation first occurs in ferrite, and strain and stress localize in ferrite prior to bainite. In the modified Crussard-Jaoul (C-J) analysis, as the yield strength ratio of bainite to ferrite (σy,B/σy,F) increases, the transition strain associated with the deformation transformation from ferrite soft phase deformation to uniform deformation of ferrite and bainite increases. Meanwhile, as the uncoordinated deformation of ferrite and bainite is enhanced, the strain localization factor (SLF) increases, especially the local strain concentration. Consequently, the yield, tensile strength, and yield ratio (yield strength/tensile strength) increase with the increase in σy,B/σy,F. Inversely, the strain hardening exponent and uniform elongation decrease.

Increasing the Wear Resistance of Marine Diesel Engines Elements Made of Ductile Iron

This paper examines the influence of austempering and shot peening on the wear resistance of ductile iron. Samples for further testing were made from mechanically processed casts. The hardness and microstructure of ductile iron were examined on the prepared samples. Metallographic analysis of ductile cast iron samples in the cast state determined the pearlitic-ferritic structure of the matrix characteristic of this type of cast iron. Pearlite predominates in the structure, and the rest consists of ferrite and graphite nodules. The samples were then austempered. The isothermal conversion was 240 °C. After austempering, the hardness was measured and the microstructure was characterized, and the changes that occurred in relation to the heat-treated ductile iron were studied. Austempering created a new austempered structure, harder than that in the cast state, which led to improved mechanical properties. A needle-like structure of lower bainite (ADI) with high-carbon austenite, untransformed austenite, martensite and graphite nodules was achieved. The selected parameters of the shot peening process deformed the surface of the ADI and achieved a mostly martensitic structure without the presence of a soft phase, which increased resistance to abrasion. Additional hardening of the substrate by the shot peening process resulted in a composite material with the properties of comparative steel parts, which are lighter, cheaper and easier to manufacture, more resistant to wear and quieter in operation. Such material should have an even wider application in mechanical engineering, and thus in the construction of marine machinery and plants.

Influence of Rigid Segment Type on Copoly(ether-ester) Properties

The growing ecological awareness of society created the tendency to replace petrochemically based materials with alternative energy carriers and renewable raw materials. One of the most requested groups of polymer materials with significant technological importance is thermoplastic elastomers (TPE). They combine the properties of elastomers such as flexibility with the typical properties of thermoplastics, like easy processing. Herein, one compares the influence of rigid segments on the properties of copoly(ester-ether). Thermoplastic polyesters based on bio-1,6-hexanediol and terephthalic (T), furanic (F), and napthalate (N) diesters, i.e., PHT, PHF, and PHN, were obtained employing melt polycondensation. Additionally, to grant elastic properties of polyesters, systems containing 50 wt.% of bio-based polyTHF®1000 (pTHF) with a molecular mass of 1000 g/mol, have been prepared. The composition and chemical structure have been determined by 1H nuclear magnetic resonance (NMR) and Fourier transformed infrared spectroscopy (FTIR) analyses. The temperatures corresponding to phase transition changes were characterized by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) analyses. The crystalline structure was examined by X-ray diffraction (XRD) analysis. Additionally, the influence of pTHF–rich segment on the tensile properties, water absorption, as well as thermal and thermo-oxidative stability, has been analyzed. It was found that incorporation of soft phase allows creation of thermoplastic elastomers with tensile characteristics comparable to the commercially available ones, by means of elongation at break higher than 500%, low values of tensile modulus, without exhibiting yield point.