Microstructural evolution along the build height of laser melting deposited TA15 alloy

This study emphasizes the TA15 alloy microstructural distribution fabricated by the laser melting deposition (LMD) technique. The motivation of the study is to analyze the microstructural features, such as grain or laths thickness, phase fraction, and porosity occurrence in the different regions along the build height, due to the complex thermal-solidification history during the laser melting deposition. During laser deposition of titanium alloy, the laser beam forms a melt pool, where the near-α and α+β alloys transform into a single β-phase, followed by rapid solidification. This process is repeated when a successive layer is deposited, where the previously deposited layers are re-melted. These thermal cycles can affect the parent microstructure in the previously deposited layers. It was identified from the results that the width of α-laths was larger in the regions near the top of the build component. In comparison, the bottom region near to substrate contained fine laths due to a steep thermal gradient and repeated thermal effect. The volume fraction of β-phase was higher in the bottom region, which could be regarded as the transformed β matrix due to the successive thermal effect in the α+β field. The results also showed shallow porosity existence in the top and near to top regions. According to the morphology and size, the formation of these pores can be attributed to the gas entrapment during the deposition process.

Implementation of the Onsager Theorem to Evaluate the Speed of the Deflagration Wave

While considering the deflagration regime, the thermal theory of combustion proposes that the mechanism of heat transfer from the flame exothermic zone to the front neighborhood reactants layer dominates the flame behavior. The introduction of the Fourier law allows a closed solution of the continuity and energy conservation equations to yield the burning velocity. It is, however, clear that this classical solution does not conform to the momentum equation. In the present work, instead of introducing the Fourier law, we suggest the introduction of a simplified version of the Onsager relationship, which accounts for the entropy increase due to the heat transfer process from the front layer to its successive layer. Solving for the burning velocity yields a closed solution that also definitely conforms to the momentum equation. While it is realized that the pressure difference across the flame front in the deflagration regime is very small, we believe that violating the momentum equation is intolerable. Quite a good fitting, similarly to the classic theory predictions, has been obtained between our predictions and some experimentally observed values for the propagation flame deflagration velocity, while here, the momentum equation is strictly conserved.

Analytical Investigation on the Evolution and Growth of β-Ti and Fe-Nb-Based Intermetallics in Diffusion Coupled Joints of Ti6Al4V|Nb|SS

Herein, solid-state diffusion-coupled joints (DCJs) were prepared in vacuum between stainless steel (SS) and Ti6Al4V by means of a pure niobium (Nb) interlayer (~200-μm thickness) using uni-axial compressive pressure of 4 MPa at 875 °C for 15 to 120 min. Interfacial characterization revealed the existence of successive layer wise Fe–Nb-based intermetallics like FeNb+(Nb) and Fe2Nb at Nb|SS interfaces of DCJs processed from 60 to 120 min, but the DCJs processed for shorter duration (from 15 to 30 min) do not reveal any intermetallics; however, the DCJs processed for 45 min revealed a single reaction layer of FeNb whereas that of Ti6Al4V|Nb interfaces revealed solid solution behaviour for all bonding time intervals. Required chemical analysis (in at. pct) of the reaction products was found out using spectroscope and X-ray diffractometer. Mechanical characterization (at 32 °C) of the DCJs was carried out with a microhardness tester and tensile testing facility. Ti6Al4V|Nb interface experienced a hardness of ~298 HV (for all bonding time), whereas Nb|SS interface experienced ~200 HV for 15 and 30 min and ~650 HV for 45 min and longer. DCJs treated for 60 min have better strength properties. Manifestation of reaction layers: FeNb, FeNb+(Nb), and Fe2Nb have significant effect on the strength. From the interfacial microhardness, path and surface of fracture surfaces characterizations, it was revealed that failure of the DCJs was transmitted seemingly along Nb|SS interfaces. The analytical finding of intrinsic diffusivity of Ti atoms in Nb along Ti6Al4V|Nb interface is higher by one order of magnitude than the diffusivity results of Fe atoms in Nb along the Nb|SS interface. Experimental evidences show that the growth of the reaction products along Ti6Al4V|Nb interface (adj. R-Square=0.982) and Nb|SS interface (adj. R-Square=0.999) follows a parabolic law. Recently, researchers considered diffusion coupling as the key technology to fabricate Ti|Al|Al-Cf biomimetic structure, graphite|Nb|Cu for fusion reactor devices, Ni|Ni3Al for MEMS applications, hybrid heat exchangers for nuclear applications, etc.

Полимерные пьезоэлементы на основе пористых пленок поливинилиденфторида и контактных электродных слоев полианилина

The preparation method to obtain the new hybrid piezoactive systems by successive layer-by-layer aniline polymerization in situ on the porous polyvinylidene fluoride films formed in the process based on melt extrusion has been elaborated. It is established by IR spectroscopy that the conducting form of polyaniline (emerald salt) is synthesized. It is proved that the samples containing two layers of polyaniline are characterized by higher electroconductivity than the single-layer ones, and its value increases with the orientation degree of the support. It is confirmed by electron microscopy that this effect is due to the higher homogeneity and ordering of the conducting layer in more oriented samples. It is shown that hybrid samples have a higher breaking strength, elastic modulus and break elongation than support. Electro- and piezoactive properties of the hybrid systems were studied by cyclic voltampermetry and piezomodulus testing using polyaniline layers as contact electrode materials. Piezoconstants of the samples were measured depending on the direction of loading.

Sol–Gel Treatments to Flame Retard PA11/Flax Composites

This work investigates the efficiency of sol–gel treatments to flame retard flax fabric/PA11 composites. Different sol–gel treatments applied to the flax fabrics were prepared using TEOS in combination with phosphorus and/or nitrogen containing co-precursors (DEPTES, APTES) or additives (OP1230, OP1311). When the nitrogen and the phosphorus co-precursors were used, two coating methods were studied: a ‘one-pot’ route and a successive layer deposition method. For the “one-pot” method, the three precursors (TEOS, DEPTES, and APTES) were mixed together in the same solutions whereas for the different layers deposition method, the three different treatments were deposited on the fibers successively, first the TEOS, then a mix of TEOS/DEPTES, and finally a mix of TEOS/APTES. After deposition, the sol–gel coatings were characterized using scanning electron microscope, electron probe microanalyzer, and 29Si and 31P solid-state NMR. When only TEOS or a mix of TEOS and DEPTES is used, homogeneous coatings are obtained presenting well-condensed Si units (mainly Q units). When APTES is added, the coatings are less homogenous and agglomerates are present. A lower condensation rate of the Si network is also noticed by solid-state NMR. When additives are used in combination with TEOS, the TEOS forms a homogenous and continuous film at the surface of the fibers, but the flame retardants are not well distributed and form aggregates. The flame retardant (FR) efficiency of the different treatments on flax fabrics was evaluated using horizontal flame spread test. The following ranking of the different systems is obtained: TEOS + Additives > TEOS > TEOS + DEPTES ~ TEOS + DEPTES + APTES > multilayers. All the sol–gel coatings improve the flame retardant properties of the flax fabric, except the multilayer treatment. Based on these results, the three most efficient sol–gels were selected to prepare sol–gel-modified flax/PA11 composites. The composite modified with only TEOS showed the best FR properties. Surprisingly, the composite modified with the phosphorus-based flame retardant (AlPi) did not exhibit improved FR properties. This effect was attributed to the fact that the amount of the FR additive deposited on the fabrics was too low.

Changes in Alberta’s Grasslands Soil pH by Adopting the Adaptive Multi-Paddock Grazing System

Grasslands account for a large percentage of earth’s terrestrial area. Soil is an important aspect of the global carbon cycle and plays a critical role in mitigating climate change. Due to poor land management, the grasslands have been greatly degraded, resulting in the grasslands becoming the most endangered ecosystem on the planet. Fortunately, there are several new techniques that can be implemented in order to help alleviate the negative impacts that the depleted grasslands have had on the earth. The Adaptive-Multi Paddock (AMP) grazing system is an innovative technique that has been introduced as a way to increase plant regrowth, improve animal performance, and increase soil organic carbon (SOC) levels. As SOC has been shown to be correlated to soil pH, there is potential for the AMP system to affect soil pH. To implement the AMP system, a rancher’s land would be divided into multiple small paddocks, and the cattle would be rotated between the paddocks more frequently. Non-AMP managed ranches include any ranch that uses traditional grazing techniques, such as low or high continuous grazing. The purpose of this project was to study the effects of the AMP grazing system on the pH of Alberta’s grassland soil. Soil samples were collected from AMP and Non-AMP managed ranches in Alberta. After the samples were separated into several layers, weighed, dried, and sieved, the pH of each soil section was recorded and analyzed. Using the data from the Albertan ranches, the AMP and Non-AMP managed ranches were compared. From this data, it appears that by using the AMP system, the pH was slightly lower across all soil depths. Soil also appeared to become more basic with each successive layer. Between Alberta’s four ecoregions, the average soil pH seemed to vary. In both AMP and Non-AMP managed ranches, the subsoil was more alkaline while the topsoil was more acidic, which could be a result of possible higher SOC concentrations. In future studies, the pH data from Alberta’s soils will be compared to the Saskatchewan and Manitoba data, which will represent all of Canada’s grassland soil. When the SOC data is collected, the pH and SOC concentration will be analyzed to establish a correlation. Ultimately, farmers might be reimbursed for the additional costs of adopting the AMP system because of the environmental benefits the system could have.

3D Prototype of Limited Lean Suspension System

3D printing is also known as Additive manufacturing (AM) process, where 3D objects are created by laying down into successive layer of material. In 1984, Charles Hull developed the technology of 3D printing from digital data and named the technique as Stereo lithography (STL) in 1986. In this project, create the prototype of Limited Lean Suspension System by using Fused Deposition Modeling (FDM) process in which the CAD model is designed in Catia v5 software and converted to STL format. The STL format is uploaded to FDM printer and works according to the G-code generated. This prototype is to study the kinematic parameters, working principle and in future research. By using Leaning application it will improves the vehicle stability, smooth cornering and fuel efficiency

An approach for functionally graded cladding of composite material on austenitic stainless steel substrate through microwave heating

In the present work, functionally graded clads of Ni-SiC material have been developed on austenitic stainless steel (SS-304) substrate through 2.45 GHZ domestic microwave applicator. The functionally graded clads were processed by the concept of hybrid heating with varying exposed microwave power levels from 180 to 900 W. The optimum exposure time of 900 W microwave power was varied with compositional gradient and it is from 300 s to 420 s. The maximum thickness achieved for functionally graded clads was 2 mm at optimum exposure power and time. The microstructural analysis of developed clads reveals that the partial mutual diffusion between each successive layer took place and it confirms the metallurgical bonding in between. The typical flower like structure of Ni-matrix has been observed in clads where the SiC particles were uniformly dispersed. The maximum functionally graded clads micro-hardness of 1020 ± 30 HV were achieved.