Sliding abrasive wear characteristic of TIG cladded TiC reinforced Inconel825 composite coating

TiC reinforced Inconel 825 alloy matrix composite coating with different weight percentage (20, 40, and 60) of TiC has been produced by TIG cladding process. With the increase in TiC percentage in the produced coating a drastic alteration in the coating morphology perceived predominantly due to the degree of melting of pre-deposited TiC particles. The sliding abrasive wear measured through the height loss of the coated pin extracted from the TiC-Inconel825 composite coatings executed against alumina abrasive wheel show the effect of TiC percentage as well as the sliding velocity during the test. The worn surfaces characterized by SEM suggested that the abrasion wear is predominant for removal of the coating along with delamination through oxidation. The coefficient of friction of the coating assessed against harden steel plate (HRC58) indicated a gradual reduction from 0.71 to 0.60 with the increase in TiC content in the TiC-Inconel825 composite coating.     

Mechanical,thermal expansion,and flammability properties of co-extruded wood polymer composites with basalt fiber reinforced shells

Basalt fiber (BF) filled high density polyethylene (HDPE) and co-extruded wood plastic composites (WPCs) with BF/HDPE composite shell were successfully prepared and their mechanical, morphological and thermal properties characterized. The BFs had an average diameter of 7 μm with an organic surfactant surface coating, which was thermally decomposed at about 210 °C. Incorporating BFs into HDPE matrix substantially enhanced flexural, tensile and dynamic modulus without causing a noticeable decrease in the tensile and impact strength of the composites. Micromechanical modeling of tensile properties for the BF/HDPE composites showed a good fit of the selected models to the experimental data. Compared to neat HDPE, BF/HDPE composites had reduced linear coefficient of thermal expansion (LCTE) values. The use of the pure HDPE and BF/HDPE layers over a WPC core greatly improved impact strength of core–shell structured composites. However, the relatively less-stiff HDPE shell with large LCTE values decreased the overall composite modulus and thermal stability. Both flexural and thermal expansion properties were enhanced with BF reinforced HDPE shells, leading to well-balanced properties of core–shell structured material. Cone calorimetry analysis indicated that flammability performance of core–shell structured composites was improved as the BF content increased in the shell layer.     

Structural characteristics and microwave dielectric properties of Zn1−xBixVxW1−xO4-based ceramics for LTCC applications

Herein, the improvement of the microwave dielectric properties and sintering characteristics of Zn_1?xBi_xV_xW_1?xO₄(x = 0–0.15)-based ceramics is reported. The results showed that an appropriate amount of doping could not only reduce the optimum sintering temperature from 1100° to 900°C, but also enhance the densification of the microstructures and increase the Q×f value from 5351 to 42525 GHz. Additionally, various structural parameters including the phase composition, crystal structure, vibrational and chemical bond characteristics that are correlated with the dielectric properties were systematically investigated. By considering the chemical bond characteristics, the first-principles calculations and the acquired Raman spectra, the interaction between W-O is stronger than Zn-O in the ZnWO₄ structure, while the interaction between V-O is stronger than Bi-O in BiVO₄. Interestingly, when the Zn_0.97Bi_0.03V_0.03W_0.97O₄-based ceramics were sintered at 900 °C, improved microwave dielectric properties were acquired (ε_r =18.32, Q×f=42525 GHz, τ_f=?67.51 ppm/°C), which provides a promising candidate in low-temperature co-fired ceramics technology.     

Effect of stoichiometry and milling processes in the synthesis and the piezoelectric properties of modified KNN nanoparticles by solid state reaction

Nanoparticles in the system (K,Na,Li)(Nb,Ta,Sb)O₃, modified KNN, were synthesized following a solid state reaction procedure. Milling of the individual carbonate and oxide raw materials was carried out before mixing of the components to optimize particle size. These mixtures were calcined at 700 °C for 2 h, obtaining nanoparticles with size ranging between 50 and 200 nm. The optimization of the raw materials particle size and the particle refinement of the carbonates during their decomposition play a key role in the formation of the modified KNN nanoparticles by solid state route. The obtained nanoparticles show tetragonal and orthorhombic phases coexistence that could be attributed in part to the lack of homogeneity of cations distribution confirmed by EDS analysis. The K⁺ cation excess on the modified KNN system produces a displacement of Li⁺ cations from the perovskite structure that is the origin of the stabilization of the orthorhombic symmetry. These nanoparticles are used to sintered ceramics with good piezoelectric properties without needing of anisotropic preparation methods. The sintered ceramics show resistance to hygroscopicity and deliquescence.     

Aqueous and enzymatic extraction processes for the production of food-grade proteins and industrial oil from dehulled yellow mustard flour

Aqueous extraction is an emerging alternative to hexane-based oilseed extraction since it eliminates the dangers associated with processing, and allows the simultaneous recovery of high-quality protein products and vegetable oils. Five different successive non-enzymatic and enzymatic aqueous extraction processes (AEPs/EAEPs) were developed for dehulled yellow mustard flour with the aim of producing food-grade protein and yellow mustard oil for industrial applications. The oil released in these processes was tied up in oil-in-water emulsions that must be destabilized to recover free oil prior to industrial utilization. This study endeavored to ascertain the extraction parameters that increase oil and protein extraction yields and reduce emulsion stability during successive AEPs/EAEPs for dehulled yellow mustard flour. The remarkable stability of the emulsions was due to the presence of protein emulsifiers of high molecular weight along with the mixed phospholipid–oleosin layer. pH adjustment for emulsion destabilization was relatively inefficient; therefore, enzymatic demulsification treatments with different proteases and phospholipases were evaluated for their ability to release free oil by hydrolyzing the targeted emulsifiers. Although protease treatments with Protex 6 L at a concentration of 2.5 wt.% were effective in recovering over 91% of the oil in the emulsions, phospholipase treatments did not modify the free oil recovery from the emulsions. The results indicated that the enzymatic aqueous extraction of dehulled yellow mustard flour did not offer sufficient improvement in usable protein recovery to warrant the extra effort and cost.     

Zinc-Modified ZSM-5 Nanozeolites Synthesized by the Seed-Induced Method: Interrelation of Their Textural,Acidic, and Catalytic Properties in DME Conversion to Hydrocarbons

The effect of the method of introduction of zinc cations and the zinc content in a nanocrystalline zeolite of the ZSM-5 type on the physicochemical and catalytic properties of the material in DME conversion to a mixture of liquid synthetic hydrocarbons has been studied. Zinc is introduced into the catalysts both during the zeolite synthesis and the ion exchange (Zn _n Al _m NZ5 and ZnNZ5, respectively). The use of nanocrystalline Zn _n Al _m NZ5 zeolites provides the formation of a mixture of liquid hydrocarbons with a high selectivity of no less than 90%; the liquid hydrocarbons contain more than 70% of isoparaffins and a small amount of aromatic compounds. An increase in the zinc loading of the Zn _n Al _m NZ5 zeolite from 0.9 to ~3% leads to an increase in the methanol content in the aqueous phase of the liquid product, an increase in the selectivity for liquid hydrocarbons, and a slight increase in the concentration of aromatic and unsaturated hydrocarbons in the mixture. In the presence of the ZnNZ5/Al₂O₃ catalyst with Zn introduced by ion exchange, the methanol content in the aqueous phase and the aromatics content in the liquid hydrocarbon mixture are significantly higher. The Zn _n Al _m NZ5 nanozeolites are characterized by a more developed external surface, a higher concentration of mesopores, and higher acidity.     

Trace sulfur promoted Fe,N-codoped carbon black as electrocatalyst for oxygen reduction reaction

Doping carbon materials with Fe and N attracts great attention due to its promising application in preparing ORR electrode with high performance and low cost. Previously, Fe, N-codoped catalyst (Fe/N/C) had been synthesized via a simple one-pot method using carbon materials, dopamine and FeCl₃ by our group. However, the unstable activity and low selectivity (electron transfer number of ∼3.5) are key problems that should be solved. Herein, trace sulfur has been introduced into Fe, N-codoped carbon black by using 2-mercaptoethanol as an adhesive sulfur precursor. By the doping of trace S atoms (∼0.25 at%) into Fe, N-codoped carbon frameworks, the ORR performance has been obviously improved simply without any re-treatment process, such as acid-etching or nitrogen supplement. The mechanism of this process has been systematically investigated by changing the amount of initial sulfur precursor. A moderate amount of trace sulfur can effectively enhance the ORR performance of Fe, N-codoped carbon black due to suitable interactions among Fe, N, S and C elements. Both the content and the state of Fe and N species on the surface of carbon black can be changed and controlled by trace sulfur. The as-synthesized 1.0 SFe/N/C catalyst exhibits a good ORR activity (E_1/2 = 0.749 V, J_k = 54.56 mA cm⁻²) and a total 4-electron selectivity. 1.0 SFe/N/C also shows better catalytic stability and methanol tolerance than 20 wt% Pt/C.     

Morphology effect of MnO2 promoter to the catalytic performance of Pt toward methanol electrooxidation reaction

Three MnO₂ samples with different well-defined morphologies including nanoplates, nanorods and corallines are prepared through a simple chemical precipitation method and used as the promoter/support for Pt electrocatalysts (denoted as Pt/MnO₂P, Pt/MnO₂-R and Pt/MnO₂C, respectively). The morphology effects of MnO₂ to the catalytic properties of Pt for methanol oxidation reaction (MOR) are intensively investigated. Results show that the catalytic properties of Pt are strongly dependent on the morphology of the promoter. Pt/MnO₂-R with MnO₂ nanorods as the promoter shows the highest catalytic properties among the MnO₂-promoted catalysts. The mass-specific activity and intrinsic activity of Pt in Pt/MnO₂-R catalyst is 0.51 A mg⁻¹_Pt and 11.54 A m⁻²_Pt, which is ca. 1.89 and 2.18 times that of commercial Pt/C catalysts (0.27 A mg⁻¹_Pt and 5.29 A m⁻²_Pt), respectively. Change in the electronic structure of Pt is responsible for the enhancement in the catalytic properties of Pt/MnO₂-R.     

塔里木盆地孔雀河古斜坡成藏条件新认识

尉犁1井是塔里木盆地东北缘第一口钻揭震旦系的井,它的钻探分析对了解孔雀河古斜坡成藏条件、确定该区下一步有利勘探区具有重要的意义。对尉犁1井中、下寒武统的岩心观察、电子探针岩样成分分析、热解分析及单井的盆模综合研究,确定塔里木盆地东北缘孔雀河古斜坡寒武系—下奥陶统烃源岩经历一次深埋热演化后,其有机质演化产物已接近石墨,不具备二次生烃的能力;寒武系—下奥陶统中早期发育的裂缝和溶蚀孔洞是古油藏的主要储集空间。研究尉犁断鼻成藏史认为,该区的成藏具有早期成藏、自生自储、一期破坏、二期调整的特点。最后根据尉犁1井失利原因讨论了孔雀河地区有利的勘探圈闭样式:原生未被断层改造的下古生界的古背斜为有利油气圈闭;其次是在古背斜上继承发育的断背斜圈闭;最后为岩性圈闭和不整合面-岩性圈闭;而古断鼻构造圈闭不是有利的油气圈闭。      

In situ synthesis and ammoxidation activity of ammonium salt of molybdophosphoric acid on VOPO4 catalysts

Two isomorphous VOPO₄ catalysts were prepared and used as support materials for the in situ synthesis of ammonium salt of 12-molybdophosphoric acid (AMPA) from their solid phase phosphate component. Formation of AMPA was confirmed by the XRD and FTIR analyses. The activity of the catalysts in the ammoxidation reaction revealed that the in situ synthesized AMPA catalysts are more active than the parent VOPO₄ catalysts in the conversion of 2-methylpyrazine to 2-cyanopyrazine.