Low Brittleness Research Articles

Recent Advances in Additive Manufacturing of Soft Magnetic Materials: A Review.

Additive manufacturing (AM) is an attractive set of processes that are being employed lately to process specific materials used in the fabrication of electrical machine components. This is because AM allows for the preservation or enhancement of their magnetic properties, which may be degraded or limited when manufactured using other traditional processes. Soft magnetic materials (SMMs), such as Fe-Si, Fe-Ni, Fe-Co, and soft magnetic composites (SMCs), are suitable materials for electrical machine additive manufacturing components due to their magnetic, thermal, mechanical, and electrical properties. In addition to these, it has been observed in the literature that other alloys, such as soft ferrites, are difficult to process due to their low magnetization and brittleness. However, thanks to additive manufacturing, it is possible to leverage their high electrical resistivity to make them alternative candidates for applications in electrical machine components. It is important to highlight the significant progress in the field of materials science, which has enabled the development of novel materials such as high-entropy alloys (HEAs). These alloys, due to their complex chemical composition, can exhibit soft magnetic properties. The aim of the present work is to provide a critical review of the state-of-the-art SMMs manufactured through different AM technologies. This review covers the influence of these technologies on microstructural changes, mechanical strengths, post-processing, and magnetic parameters such as saturation magnetization (MS), coercivity (HC), remanence (Br), relative permeability (Mr), electrical resistivity (r), and thermal conductivity (k).

Production of biodegradable composite plates from cross-linked starch and cellulosic fibers

Plastic used in food packaging causes permanent damage to living things. Therefore, biodegradable packaging has gained importance. In this study, biodegradable composite plates made from cross-linked wheat starch and cellulose-based fibers were examined for their physical and mechanical properties. The mechanical and physical properties were significantly altered when the obtained composite plates were examined. According to texture analysis, the plate with the lowest brittleness and with the highest crushing toughness value was produced from 7% carboxymethylcellulose. The densities of the composite plates obtained from cross-linked wheat starch were found to be 0.171 g/cm³, and their densities were found to be lower than the composite plates produced from natural wheat starch. It was determined that the plate with the highest water resistance was produced from 7% carboxymethyl cellulose. Added cellulosic fibers (commercial cellulose, linter fiber, hemp fiber) reduced moisture absorption from the air, reducing the average moisture content to 8.71. All of the plates produced with 7% linter fiber, which has the lowest moisture content, completely disappeared from nature within 40 days.

Thermoplastic starch hybrid biocomposite films with improved strength and flexibility produced through crosslinking via carboxylic acid

Thermoplastic starch (TPS) suffers from its intrinsic low mechanical strength and high brittleness due to its strong hydrogen bonding and low chain mobility. The conventional way to crosslink the TPS film can improve the strength and stiffness of the films, but usually reduces the flexibility of the film, and increases its brittleness. In this study, the incorporation of the hybrid nanofiller [1 wt% nanocellulose (C) and 4 wt% nano bentonite (B)] into the TPS proved to improve greatly the films’ strength and flexibility. The hybrid nanofillers with ratio 4B:1C was incorporated into the crosslinked thermoplastic corn starch (CR-TPCS) film to increase the its flexibility and toughness and produced a high mechanical strength fully biodegradable film. Two different aqueous carboxylic acids: citric acid (CA) and tartaric acid (TA) with different pH values (2,4,6) as the green crosslinker were employed. Substantial increase of tensile strength (3.98 to 9.17 MPa), Young’s modulus (9.10 to 46.30 MPa) and elongation at break (55.2 to 135.7%) was observed for the CA- 4B1C/pH2 films compared to the CR-TPCS films. The melting temperature (Tm) of the CA-4B1C/pH2 improved compared to the TPCS/4B1C (un-crosslinked) film due to its crosslinking effect. Meanwhile, the CA-4B1C films exhibited the highest degree of substitution and di-esterification with the lowest swelling and water solubility properties due to the formation of a special “bridge” structure between the CA, nanocellulose and plasticizer. The “bridge” structure developed between the TPCS chains serves as the toughener to motivate higher chain stress relaxation and load endurance. The crosslinked “bridge structure” also proved to effectively reduce the retrogradation phenomenal in the TPCS films. This combination method of hybridization and crosslinking is an efficient, low cost, and environmentally friendly technique to overcome the low flexibility and brittleness problem of the TPS based packaging film.

Revealing microstructural evolution and mechanical properties of resistance spot welded NiTi-stainless steel with Ni or Nb interlayer

Dissimilar welding of NiTi and stainless steel (SS) for multifunctional device fabrication is challenging due to the brittle nature of intermetallic compounds (IMCs) that are formed in the weld zone. In this work, Ni and Nb interlayers were applied for the resistance spot welding (RSW) of NiTi and SS to replace the harmful Fe2Ti phase and to restrict the mixing of dissimilar molten metals, respectively. Microstructural evolution and mechanical properties of the joints were investigated. It was shown that a conventional weld nugget was created in the absence of any interlayer in the welded joint suffering from traversed cracks due to the formation of brittle IMCs network in the fusion zone (FZ). By the addition of Ni from the interlayer, Fe2Ti dominated weld nugget was efficaciously replaced by Ni3Ti phase; however, the presence of the large pore and cracks reduced the effective joining area. The use of a Nb interlayer resulted in a fundamentally different joint, in which FZs at NiTi and SS sides separated by the unmolten Nb would suppress the mixing of dissimilar molten metals. Nb-containing eutectic structures with low brittleness formed at the interfaces, contributing to the enhancement of joint strength (increased by 38% on fracture load and 460% on energy absorption). A high-melting-point interlayer showed great potential to realize a reliable and high-performing RSWed NiTi-SS joint.

Eccentric compression behavior of seawater and sea sand concrete columns reinforced with GFRP and stainless steel bars

Using FRP bars instead of steel bars to reinforce concrete columns in harsh environments has become an important method for solving corrosion problems. FRP bars have high tensile strength but low compressive strength and high brittleness, while stainless steel (SS) bars have high tensile and compressive strength and good ductility. Therefore, this paper studied the eccentric compression behavior of seawater and sea sand concrete (SSC) columns reinforced with GFRP and SS bars, in which GFRP bars were arranged on the tension side and SS bars were arranged on the compression side to improve the ductility and to analyze the effect of axial stiffness of reinforcement on the N-M interaction diagrams. A total of 48 SSC columns were designed, of which 20 were reinforced with GFRP and SS bars, 14 were reinforced with GFRP bars and 14 were reinforced with SS bars. To analyze the eccentric compression performance of SSC columns and propose the bearing capacity calculation equation, test variables were designed, including the reinforcement type, reinforcement ratio, and eccentricity, to ensure that the equation had certain universal applicability. The three failure modes of compression failure, combined compression-bending failure, and bending failure were found with the increase in the eccentricity for the GFRP and SS bars reinforced SSC (GFRP-SS-SSC) columns. The ductility indices of the GFRP-SS-SSC columns were approximately 1.5 times those of the GFRP bars reinforced SSC columns, which indicated that the ductility could be improved by replacing the compression GFRP bars with SS bars. Finally, the theoretical N-M interaction diagrams were established through the cross-section force analysis and compared with the experimental N-M interaction diagrams. Moreover, the failure mode is influenced by varying the axial stiffness of the longitudinal bars on both sides of the column section by analyzing the N-M interaction diagrams.

Impact of Nano-CaCO3 and PVA Fiber on Properties of Fresh and Hardened Geopolymer Mortar

Geopolymer is a green substitute for Portland cement but has low tensile strength, high brittleness and easy cracking. Therefore, fibers and nanomaterials are used to strengthen and toughen geopolymer composites. The influence of nano-calcium carbonate and PVA fiber on the properties of fresh and hardened geopolymer mortar were studied herein. The hybrid of long and short fibers with small content (0.8 vol.%) is conducive to flowability, while the hybrid with large content (1.6 vol.%) and nano-calcium carbonate is conducive to flowability. The slump flow and flow rate of geopolymer mortars with low fiber factor (product of fiber volume fraction and length-diameter ratio) decrease with the growth in nano-calcium carbonate content. As the PVA fiber factor reaches 464.8%, the slump flow and flow rate values of mortars with 0, 1 wt.% and 2 wt.% nano-calcium carbonate are close to each other. About 450% is the density packing threshold of PVA fiber in geopolymer composites. The combination of 0.8 vol.% 12 mm + 0.4 vol.% 6 mm fiber + 1 wt.% nano-calcium carbonate presents the highest flexural strength and flexural to compressive strength ratio, with a compressive strength of about 36 MPa. The optimal fiber factor range of PVA fiber in cement and geopolymer mortar is about 400% and higher than 600%, respectively. PVA fibers show more effective enhancement of flexural strength and toughness in geopolymer than cement mortar. The ultrasonic wave velocity and apparent density of geopolymer mortar show a downward trend as a whole with the increase in fiber factor. The intensity rise of the hump between 17° and 38° (2 θ) in the XRD pattern is observed. The SEM indicates that the surface of PVA fiber in geopolymer mortar with nano-calcium carbonate is heavily scratched, and the fiber filaments are rolled up, demonstrating improved bonding between PVA fiber and geopolymer mortar.

Mechanically Robust Ultrathin Solid Electrolyte Membranes Using a Porous Net Template for All-Solid-State Batteries.

All-solid-state batteries (ASBs) have been identified as a potential next-generation technology for safe energy storage. However, the current pellet form of solid electrolytes (SEs) exhibits low cell-level energy densities and mechanical brittleness, and this has hampered the commercialization of ASBs. In this work, we report on the development of an ultrathin SE membrane that can be reduced to a thickness of 31 μm with minimal thermal shrinkage at 140 °C, while exhibiting robust mechanical properties (tensile strength of 19.6 MPa). Due to its exceptional ionic conductivity of 0.55 mS/cm and the corresponding areal conductance of 84 mS/cm2, the SE membrane-incorporated ASB displays cell-level gravimetric and volumetric energy densities of 127.9 Wh/kgcell and 140.7 Wh/Lcell, respectively. These values represent a 7.6- and 5.7-fold increase over those achieved with conventional SE pellet cells. Our results demonstrate the potential of the developed SE membrane to overcome the critical challenges in the commercialization of ASBs.

Improving the hot air drying of garlic slices by perforation synergistic alcohol pretreatment

Long processing time represents a serious challenge in hot air drying since it led to high energy consumption and quality deterioration. A synergistic pretreatment of artificial perforation and alcohol maceration (PAT) was proposed in this study to improve hot air drying of garlic. Samples without pretreated, perforated, and subjected to alcohol pretreatments were used as control. The results showed that PAT pretreatment significantly reduced the drying time and energy consumed by 36.67%. Analysis showed that the mechanisms underlying the highest drying rate of PAT pretreated sample included pre-dehydration, capillary flow promotion and cell permeability enhancement. Samples pretreated with PAT exhibited the highest whiteness value, minimum shrinkage, lowest brittleness, and especially the highest content of volatile components, which is essential for its application as a spice. The antioxidant activity, total phenolics and allicin content were low in the PAT samples compared with other samples. This study provides a simple and effective approach to improve the drying of garlic.

A review on high entropy silicides and silicates: Fundamental aspects, synthesis, properties

AbstractMetal silicides and silicates belong to the silicon‐based non‐oxide and oxide ceramics family with exceptional properties. Silicides face fatal oxidation at low temperatures and intrinsic brittleness, whereas silicates face instability in phase at high temperatures which restricts its usage in vast engineering applications. Hence, the ceramic community introduced the concept of high entropy in metal silicides and silicates. Since 2019, high entropy silicides and silicates, a multicomponent system, have created new avenues for materials discovery and design. High entropy silicides displayed elevated properties than the traditional silicides aiming its applications in microelectronic, high‐temperature oxidation resistance coatings, and structural materials. Similarly, high entropy silicates displayed improved properties than the traditional silicates making them the most promising materials for environmental and thermal barrier coating applications for hot section components in gas turbines. The review focuses on specific case studies to emphasize the latest research and developments in high entropy silicides and silicates. Synthesis approaches employed in developing high entropy silicides and silicates and their structural and microstructural outcomes are addressed. The possible application is predicted based on the overview of the properties explored to date. The review concludes with future possibilities offered by the high entropy silicides and silicates.

Improvement of Natural Polymeric Films Properties by Blend Formulation for Sustainable Active Food Packaging.

Active packaging manufactured with biopolymers extracted from agri-food waste is one of the most innovative and eco-sustainable strategies for maintaining food quality. However, biopolymers often present poor performances, which hinders their competitiveness compared with plastics. This work focused on developing and optimizing a natural polymeric blend produced by solvent casting based on zein and chitosan to improve the pure biopolymers' properties. The best results were obtained by blending zein and chitosan in a 1:2 weight ratio. The films were characterized in terms of morphology, mechanical and oxygen barrier properties, thermal stability, transparency and wettability. The blend production allowed us to obtain lower brittleness and lower stiffness materials compared with pure polymer films, with oxygen permeability values two orders of magnitude lower than pure zein, better optical properties with respect to pure chitosan and good thermal stability. The wettability properties of the blend did not result in being altered with respect to the single polymer, which was found to have hydrophilic behavior, highlighting the strong influence of glycerol used as a plasticizer. The results suggested that the polymer blending strategy is a viable and cost-effective method for producing packaging materials as alternatives to plastics.

Additive Manufacturing of Carbon Fiber Reinforced Epoxy Thermoset with Improved Thermomechanical Properties

Laser Powder Bed Fusion (LPBF) is a widely used additive manufacturing technique for powder-based polymers and metallic materials. Thermoplastics like Polyamide 12 and Polyamide 6 are commonly used in LPBF; thermosetting polymers are gaining attention due to their superior stability. Epoxies are a popular thermoset, but some exhibit low physical properties and brittleness, leading to reduced toughness. The work presented in this paper explores the effect of using short carbon fibers (CF) as additives to epoxy-based thermosetting material on physical and thermomechanical properties. A total of six epoxy thermoset/CF composite powder blends were prepared by varying reinforcing materials weight percentages (0 wt%, 0.3 wt%, 0.6 wt%, 1 wt%, 5 wt%, and 10 wt%). Tensile, four-point bending, and dynamic mechanical analysis (DMA) test samples were printed using the LPBF technique. Significant improvements in the physical and thermomechanical properties were obtained in the thermoset composites with 5 wt% of CF due to good adhesion between reinforcing materials and the matrix and a low level of porosity. Fracture surface analysis was performed via scanning electron microscopy (SEM), which provided insight into the influence of CF on the properties of thermosetting composites. The findings of this research demonstrate the feasibility of improving the inferior physical and thermomechanical properties of 3D-printed CF-reinforced epoxy. With a certain amount of CF reinforcement, Young’s modulus and fracture modulus can be increased by around 52% and 259%, respectively.

Experimental research on flexural behavior of post-tensioned self-compacting concrete beams with recycled coarse aggregate

Self-compacting concrete with recycled coarse aggregate (RCASCC) is a green concrete material with high performance. However, it bears the disadvantages of low elastic modulus and high brittleness compared with ordinary concretes. In this study, recycled coarse aggregate (RCA) obtained from C30 concrete block discarded in laboratory research and tests was used to produce post-tensioned self-compacting concrete (PSRC) beams, while coarse natural aggregate (NCA) was used to produce post-tensioned natural concrete (PNC) beams. The four-point bending tests were carried out on PSRC and PNC beams to analyze the variations between the flexural performance of PSRC and PNC beams. In addition, we discuss the applicability of the current design codes on PSRC beams. The results reveal that the failure mode of PSRC beams is similar to that of PNC beams, whereas it differs significantly in the number and scope of cracks. Moreover, the variations can be reduced by increasing the ratio of non-prestressed reinforcement. In general, the PSRC beam is more ductile than the PNC beam. The increase in the ratio of non-prestressed reinforcement reduced the ductility of the PSRC beam as well as the fluctuations in the ductility of PSRC and PNC beams. Compared with the PNC beam under the same conditions, the PSRC beam exhibited a similar flexural capacity, the cracking load and maximum crack width decreased significantly, and its working deflection increased slightly. According to the calculation and analysis, ACI318-08 can be applied for calculating the cracking load, flexural capacity, and working deflection of the PSRC beams, but not the maximum crack width; GB50010-2010 is applicable for calculating the cracking bending moment and flexural capacity of PSRC beams, but the calculation deviation of the working deflection and maximum crack width is large; EN1992-1-1:2004 is applicable for calculating the crack bending moment of PSRC beams, but it is not safe for evaluating the bending capacity, working deflection, or maximum crack width. Overall, the average crack spacing correction formula proposed through experimental tests in this study can be applied to determine the maximum crack width of PSRC beams, and its accuracy is higher than that of the above-stated specifications.

Study of the brittleness mechanism of aluminum/steel laser welded joints with copper and vanadium interlayers

Intermetallic compounds (IMCs) generated by direct laser welding of aluminum and steel decrease the strength of the joint. To evaluate the effect of alloying elements on the weldability of aluminum/steel dissimilar materials, the copper (Cu) and vanadium (V) were introduced into the interlayer to inhibit the generation of Fe-Al IMCs. Comparing with direct welding, Cu promotes the generation of Al2Cu and V transforms the disordered Fe/Al interface into a continuous Al/V interface to promote the generation of Al3V and Al21V2. In addition, the first-principles calculations were carried out to study the elastic properties and electronic properties of intermetallic compounds. The results show that high brittleness of FeAl, Fe2Al5 and FeAl3 results from strong covalent bonding and antibonding. The Fe(d) orbit hybridizes with Al(s) and Al(p) orbits while resonant peaks and wide pseudogap appear in the density of states. The low brittleness of Al2Cu results from the less count of covalent bonds with 76.2% of weaker antibonding; the low brittleness of Al21V2 results from the lower covalent bond strength with a maximum overlap bond population of 0.265. With the addition of Cu, the strength of the joint was increased to 63 MPa from 31 MPa. Furthermore, the addition of V completely prevents the formation of Fe-Al IMCs, which results in the highest joint strength (93 MPa). The results of the first-principles calculations and experiments are in good agreement.

Effect of electrospun stereocomplex PLA fibers and modified cellulose nanocrystals on crystallization of poly(L‐lactic acid)

AbstractPoly(L‐lactic acid) (PLLA) is a biodegradable polymer that has attracted increasing attention due to its fantastic properties. Nevertheless, the disadvantages of PLLA, such as low crystallization rate and brittleness, limit its wide commercial applications. In the present work, electrospun stereocomplex PLA fibers (Sc‐fibers) and PLLA grafted cellulose nanocrystals (g‐CNCs) are prepared as nano‐fillers and then blended with PLLA matrix to prepare different nanocomposites. Both of nano‐fillers would accelerate the crystallization rate of PLLA, and as expected, g‐CNCs have much stronger nucleation ability towards PLLA than Sc‐fibers. Nevertheless, the crystallization of PLLA will decrease to some extent in the presence of both nano‐fillers of g‐CNCs and Sc‐fibers due to the preferential formation of stereocomplex crystals on the surfaces of CNCs. Moreover, the presence of nano‐fillers would enhance the mechanical properties of PLLA, such as the elongation at break can increase by four times after incorporating both g‐CNCs and Sc‐fibers. This work provides a new consideration for designing different nano‐fillers, especially for polymer matrices with low crystallization ability and brittleness.

Microstructure and properties of magnesium/steel dissimilar metals by interlayer assisted laser welding

AbstractThe experiments of laser welding were carried out for AZ31B magnesium alloy and DP590 dual-phase steel in an overlap magnesium-on-steel configuration with interlayer addition. The interlayer elements were selected based on the calculation of thermodynamic properties and intrinsic mechanical properties, and the changes of microstructure and properties of magnesium/steel joint were analyzed. The results showed that with the addition of Sn and Al interlayers, the maximum load of the joint was 730 and 590 N, respectively, which was 2.04 times and 1.46 times higher than that without interlayer. With the addition of Al interlayer, the brittle Mg17Al12 compound was formed at the magnesium/steel interface, which limited the improvement of the mechanical performance of magnesium/steel joint. In the case of adding Sn interlayers, Mg2Sn with relatively low brittleness and Fe3Sn with a certain ductility were formed at the magnesium/steel interface, which was a vital reason that the properties of joint with Sn interlayer were higher than those with Al interlayer.

Mechanical properties of steel reinforced coral aggregate concrete column under uniaxial compression

The production of coral aggregate concrete (CAC) from coral debris effectively addresses the lack of building materials in island construction. Due to the low compressive strength and visible brittleness of CAC, steel reinforcement with anti-rust treatment is adopted to improve the mechanical properties of CAC. This paper presents an experimental study on the mechanical behavior of 45 anti-rust coated steel reinforced coral aggregate concrete (RCAC) columns under uniaxial compression, designed with the consideration of concrete strength and configurations of the transverse reinforcement. The test results show that the volumetric ratio of lateral confinement can improve the compressive strength and ductility of RCAC effectively. The strengthening effect of diamond-shaped composite and spiral hoop is higher, while that of rectangular hoop is slightly weaker. The increase of concrete strength has a significant positive effect on the peak stress, but not on the peak strain. Based on the experiments, the formulae for the peak stress and peak strain of RCAC are given, and the constitutive model of RCAC is proposed. Moreover, the calculation method of the theoretical bearing capacity is arrived at, and the predicted values with a specific safety reserve are close to the measured values.

Mechanical properties and brittleness of concrete made by combined fly ash, silica fume and nanosilica with ordinary Portland cement

<abstract> <p>This paper introduced a new concrete composites made by quaternary binder by partially replacing ordinary Portland cement (OPC) with different percentages of supplementary cementitious materials (SCMs). The motivation is to reduce our dependency on OPC to reduce CO<sub>2</sub> emission and carbon foot print. As the main substitute for the OPC, siliceous fly ash was used (FA). Moreover, silica fume (SF) and nanosilica (nS) were also used. This study utilized the following contents of SCMs used: 5% of nS; 10% of SF; 0, 15, and 25% of FA. During examinations the main mechanical properties of concrete composites, i.e. compressive strength (<italic>f</italic><sub>cm</sub>) and splitting tensile strength (<italic>f</italic><sub>ctm</sub>) were assed. The brittleness of these materials was also analysed. Based on the conducted studies, it was found that concrete composite based on quaternary blended cements, of series Mix3, has shown the best results in terms of good strength parameters, whereas the worst mechanical parameters were characterized by concrete of series Mix4. On the other hand, concrete including only SF and nS (Mix2 series) were characterized by the greatest brittleness. It was observed that <italic>f</italic><sub>cm</sub> of concrete composites for series Mix2, Mix3, and Mix4 increase of 41%, 48%, and 31% respectively compared with the concrete without additives, i.e. series Mix1. In addition, <italic>f</italic><sub>ctm</sub> also increase of 39%, 47%, and 30%, respectively, for the three series mentioned above, compared with the control concrete. Concrete of series Mix3, with high mechanical properties and demonstrating the features of quasi-plastic material, i.e. having lower brittleness, can be used in concrete and reinforced concrete structures subjected mainly to dynamic and cyclic loads. Therefore, it can be used, in the construction of foundation structures for machines and other types of structures in which the above-mentioned loads are dominant.</p> </abstract>

Experimental study on the preparation of magnesium oxysulfate cement-based composites using waste locust powders to replace non-renewable magnesium oxide

Magnesium oxysulfate cement is a new type of environment-friendly cement with low energy consumption and promising development potential. But the raw material MgO is not renewable. To improve the utilization of forestry wastes and save MgO, composites containing locust powders with 0 ∼ 25 % mass of MgO were prepared by mechanical mixing and curing for 3d ∼ 100d. The slurry’s fluidity, mechanical property, water resistance and microstructure were studied. Strength data at 100d were found to be essential for property evaluation. The maximum locust dosage based on fluidity was 25 %, and composites with 10 %∼25 % locust exhibited flexural strength of 13.37 ∼ 15.12 MPa and compressive strength of 56 ∼ 64.3 MPa at 100d. The corresponding flexural strength improvement and compressive strength reduction comparing to cement with no locust were by 13.5 %∼28.35 %, and 21.86 %∼31.95 %, respectively. Regarding relations of flexural force and displacement before fracture at 100d, locust with 10 %∼25 % dosage improved the displacement and energy absorption capacity by 56.88 %∼125.58 % and 52.48 %∼108.49 %, showing lower brittleness. Composites containing 10 %∼25 % locust improved the flexural strength by 14.23 %∼48.82 % when soaking in water, and the softening coefficient was larger than 0.85 if cured for 35d and soaked for 7d, indicating good water resistance. Effects of locust dosage on primary functional groups, phase changes, thermal stability and microstructure were analyzed by various techniques. A new optimization method based on seven indicators is proposed, capturing the optimal locust dosage as 20 % mass of MgO. This paper proposed an environmental-friendly approach to improve the utilization of forestry wastes and develop new cement-based building materials.

The formation and architecture of Penglai granite intrusion reservoir along the Tanlu strike-slip fault: Implications for basement exploration in the offshore Bohai Bay Basin, North China

The hydrocarbon in the basinal basement mostly occurs in the topmost of buried hills along the unconformity, while we present a special play in architecture with the oil-bearing in the lower geomorphic position at the Penglai buried hill. Based on the cores, thin sections, whole rock X-ray, physical property, well logging, and seismic data, we investigated the characteristics of the reservoirs of the Penglai oilfield and discussed the controlling of strike-slip activity, weathering, and lithology on the reservoir in this paper. The results show that the Penglai buried hill reservoirs were mainly distributed in the fractured and weathered granites. The quality of the reservoir is related to mechanics and weathering dissolution behavior among different rocks. The strong dextral strike-slip activity of the Tanlu strike-slip fault zone during the Paleogene resulted in the strong uplift of the Penglai buried hill and also provided the stress condition for tectonic fractures to develop. The dissolution of atmospheric water along the tectonic fractures further improved the reservoir’s physical properties during the nearly 30Ma exposure interval. Compared to granite rocks, mica quartz schist, with higher content of the femic mineral and lower content of feldspar, presents lower brittleness and less soluble minerals. Therefore, the relatively stronger of weathering resistance of mica quartz schist resulted in a higher ring-landform in buried hill geomorphology which surrounds the granite intrusion, controlling the special oil play in architecture with hydrocarbon accumulated in the lower-seated granite reservoir underlying the unconformity.

SHS of highly dispersed powder compositions of nitrides with silicon carbide Review

The application of the process of self-propagating high-temperature synthesis (SHS) to prepare highly dispersed powder nitride-carbide compositions from the most common refractory nitride (Si3N4, AlN, TiN) and carbide (SiC) compounds with a particle size of less than 1 μm is considered. The advantages of composite ceramics over single-phase ceramic materials and such trends of its development as the transition to nanostructured ceramics and the application of in situ processes of direct chemical synthesis of nanoparticles of components in the composite body are described. The attractiveness of the SHS process as one of the promising in situ processes characterized by simplicity and cost-effectiveness, the possibility of obtaining highly dispersed ceramic powders by burning mixtures of inexpensive reagents is shown. Considerable attention is paid to the consideration of the results of the application of azide SHS, based on the use of sodium azide and gasified halide salts as part of mixtures of initial powders of nitrided and carbidized elements during their combustion in nitrogen gas. The review of publications devoted to the application of SHS to obtain highly dispersed composite powders Si3N4–SiC, AlN–SiC and TiN–SiC, promising for use in sintering of the corresponding composite ceramic materials of submicron and nano-sized structure with improved properties, lower brittleness, good machinability, lower sintering temperatures compared with single-phase ceramic materials made of nitrides or carbides as well as for other applications, is presented. The results of the application of azide SHS are presented in detail both in the form of the results of thermodynamic calculations and the results of experimental research of combustion parameters, combustion product structure and composition. The advantages and disadvantages of using the combustion process for the synthesis of nitride compositions with silicon carbide, the causes of the disadvantages and the directions of further research to eliminate them are discussed.