Ablation behavior of (Hf–Ta–Zr–Nb–Ti)C high-entropy carbide and (Hf–Ta–Zr–Nb–Ti)C–xSiC composites

The ablation behavior of (Hf–Ta–Zr–Nb–Ti)C high-entropy carbide (HEC-0) was investigated using a plasma flame in air for different times (60, 90, and 120 s) at about 2100°C. The effect of SiC content on the ablation resistance of HEC–xSiC composites (x = 10 and 20 vol%) was also studied. The linear ablation rate of HEC-0 decreases with increasing ablation time, showing the positive role of the oxide layer with a complex composition. The linear ablation rate of HEC–10 vol% SiC (0.3 µm s⁻¹) is only a 10th of that of HEC-0, showing a significant improvement in ablation resistance, probably due to the formation of a protective oxide layer containing melted SiO₂ and refractory Hf–Zr–Si–O oxides.     

Adhesion at Poly(Butylacrylate)–Poly(Dimethylsiloxane) Interfaces

We present an investigation of the adhesion modulation mechanisms of silica-like nanoparticles (MQ resins) incorporated in polydimethylsiloxane (PDMS) elastomers and acrylic adhesives. The Johnson-Kendall-Roberts (JKR) test has been used to gain information on the both zero velocity and the velocity dependence of the adhesive strength, avoiding as much as possible contributions to the adhesive strength of bulk dissipation in the adhesive (which is not the case with peel tests). As the incorporation of the MQ resins into the elastomers deeply affects their own mechanical properties, the loading and unloading curves of small poly(butylacrylate) (PBA) lenses on either PDMS elastomers, adsorbed PDMS and pure MQ resin layers are compared in a systematic manner. The PBA chains are observed to have a neat affinity for the MQ resin nanoparticles. When MQ resins are present at the interface, they tend to prevent facture propagation, thus producing a larger deformation of the PBA lens. The modulation of adhesion is then dominated by the corresponding dissipation inside the acrylic adhesive.     

Nanosized micelles self-assembled from amphiphilic poly(citric acid)–poly(ε-caprolactone)–poly(citric acid) copolymers

In this study, novel ABA-type amphiphilic copolymers consisting of poly(citric acid) (PCA) (A) as hydrophilic segment and poly(ε-caprolactone) (PCL) (B) as hydrophobic block were prepared by an approach in the following two steps: (1) ring-opening polymerization (ROP) of ε-caprolactone with 1,5-pentanediol initiator to obtain a hydroxyl telechelic PCL; (2) melt polycondensation reaction of hydroxyl telechelic PCL and citric acid molecules. The prepared copolymers are capable of self-assembling into nanosized micelles in aqueous solution. The influence of the copolymer composition on the micelle dimensions was investigated. The critical micellar concentration of the copolymers is in the range of 5–6.3 × 10^?2 mg/mL which is determined by the fluorescence probe technique using pyrene. Also the results indicate that CMC of self assembled micelles is influenced by the hydrophilicity of PCA–PCL–PCA copolymers depending on the CA/CP ratio, and these micelles may find great potential as drug carriers in biomedical fields.     

1–(3–硝基–2–吡啶)–1H–苯并三唑的合成与表征

以苯并三氮唑和2–氯–3–硝基–吡啶为原料,合成出1–(3–硝基–2–吡啶)–1H–苯并三唑。采用元素分析、核磁共振光谱等手段鉴定了目标产物结构,并用DSC测定了产物的熔点。考察了反应溶剂、溶剂用量、缚酸剂种类、缚酸剂用量对该反应收率和产品纯度的影响。确定的最佳工艺条件为:以工业乙醇为反应溶剂,溶剂与反应物的原料比为200 mL∶0.1 mol,Na2CO3为反应缚酸剂,缚酸剂与苯并三氮唑的摩尔比为1∶1,反应时间为12 h。     

Y_(0.08)Sr_(0.92)Ti_(1–x)Fe_xO_(3–δ)混合导体材料的电子–离子阻抗行为

采用溶胶–凝胶法制备Y_(0.08)Sr_(0.92)Ti_(1–x)Fe_xO_(3–δ)(x=0.2,0.3,0.4,0.5)混合导体材料,用X射线衍射(XRD)分析该材料的物相组成,采用交流阻抗法和电子阻塞电极法分别测定材料的总电导率与离子电导率,研究铁含量对Y_(0.08)Sr_(0.92)Ti_(1–x)Fe_xO_(3–δ)混合导体材料的结构、电性能及阻抗行为的影响。结果表明:样品均为单一立方相钙钛矿结构;在测试温度范围内,随Fe掺杂量增加,Y_(0.08)Sr_(0.92)Ti_(1–x)Fe_xO_(3–δ)的总电导率和离子电导率都随着温度的升高而增大。800℃以下,Y_(0.08)Sr_(0.92)Ti_(1–x)Fe_xO_(3–δ)(x=0.2,0.3,0.4,0.5)的总电导率为0.017~0.110 S·cm–1,离子电导率为0.010~0.024 S·cm–1。     

Substituted Mo–V(Ti)–Te(Ce)-oxide M2 Catalysts for Propene Ammoxidation

One of the most effective propane to acrylonitrile ammoxidation catalyst is comprised of the two phases M1 (orthorhombic) Mo_7.5V_1.5NbTeO₂₉ and M2 (pseudo-hexagonal) Mo₄V₂Te₂O₂₀. Under reaction conditions, the two phases work in symbiosis with each other where M1 is the paraffin activating component and M2 is the olefin activating component. Since the catalytic improvement of either phase should result in an enhancement of the overall acrylonitrile yield, controlled substitution of certain elements in either or both phases might result in the desired improvement. Our current study concentrates on the partial substitutions of V with Ti and Te with Ce in the M2 phase. Ti substitution results in a considerable propene activity improvement, whereas the selectivity to acrylonitrile is unaffected. Substitution with Ce, on the contrary, substantially improves the selectivity to acrylonitrile. Also, a minor improvement of the activity is notable. The acrylonitrile selectivity improvement is a result of better NH₃ utilization and comes at the expense of reduced acrolein make. XRD reveals that all of the substituted compositions retain the M2 structure and essentially are monophasic. XANES recordings show for the bulk that the Mo is 6+, the V is 4+, or 4+ and 5+ when Ce is present, the Ti is 4+, the Ce is 3+, and the Te 4+ with some 6+ also present. According to the ESR data, in the M2 with Ce (7Te/3Ce) only 21% of the V is 4+, the remainder being 5+, which tentatively can be explained by the existence of some cation vacancies in the hexagonal channels. HRTEM imaging reveals little if any differences between the materials, all have the typical pseudo-hexagonal habit of the M2 phase and expose a 1–2 nm thick surface layer without any apparent long-range ordering. XPS data show that all catalysts, including the base, are highly enriched at the surface with Te at the expense of other metals. The 7Te/3Ce composition exhibits also substantial Ce surface enrichment. Moreover, the valences of the cations at the surface differ from the bulk in that for all fresh catalysts V is 5+ and Te is 6+ on the surface. Characterization by XPS of catalysts used in propene ammoxidation, reveals reduction of Te and, except when Ce is present, also Mo. Therefore, it might be inferred that the surfaces of the catalysts studied here are comprised essentially of one or a few monolayers of TeMoO or TeCeMoO on an interacting M2 crystalline base.     

Wear behavior of (Mo–Nb–Ta–V–W)C high-entropy carbide

Wear characteristics of an (Mo–Nb–Ta–V–W)C high-entropy carbide were investigated using ball-on-flat technique. The experimental material with a high relative density of 99.0%, single phase, average grain diameter of 10.7 μm, and nanohardness of grains 28.6 GPa was prepared by ball-milling and two-step field-assisted sintering. The tribological test was realized during dry sliding in air with the SiC ball as tribological partner at applied loads 5, 25, and 50 N. The microstructure, deformation, and damage characteristics were studied using scanning electron microscopy and confocal electron microscopy. The friction coefficient values during the test with 5 and 25 N were very similar and stable, with a value of approximately .4, whereas during the test with 50 N, it decreased from the value of .48–.42. The specific wear rate increased with increasing load from 3.71 × 10^–7 mm³/N m at 5 N to 2.59 × 10^–6 mm³/N m at 50 N. The dominant wear mechanism was mechanical wear with intensive grains pullout, fracture, and powder formation, without visible tribochemical reactions and tribo-layer formation. The wear rate decreased due to the created rolling contacts among the tribopartners thanks to the hard and spherical nanopowders present.     

Multifunctionality of Active Centers in (Amm)oxidation Catalysts: From Bi–Mo–O x to Mo–V–Nb–(Te, Sb)–O x

Catalytic centers in selective (allylic) oxidation and ammoxidation catalysts are multimetallic and multifunctional. In the historically important bismuth molybdates, used for propylene (amm)oxidation, they are composed of (Bi³⁺)(Mo⁶⁺)₂ complexes in which the Bi³⁺ site is associated with the -H abstraction and the (Mo⁶⁺)₂ site with the propylene chemisorption and O or NH insertion. An updated reaction mechanism is presented. In the Mo–V–Nb–Te–O _x systems, three crystalline phases (orthorhombic Mo_7.5V_1.5NbTeO₂₉, pseudohexagonal Mo₆Te₂VO₂₀, and monoclinic TeMo₅O₁₆) were identified, with the orthorhombic phase being the most important one for propane (amm)oxidation. Its active centers contain all necessary key catalytic elements (2V⁵⁺/Mo⁶⁺, 1V⁴⁺/Mo⁵⁺, 2Mo⁶⁺/Mo⁵⁺, 2Te⁴⁺) for this reaction wherein a V⁵⁺ surface site (V⁵⁺ = O ⁴⁺V–O) is associated with paraffin activation, a Te⁴⁺ site with -H abstraction once the olefin has formed, and a (Mo⁶⁺)₂ site with the NH insertion. Four Nb⁵⁺ centers, each surrounded by five molybdenum octahedra, stabilize and structurally isolate the catalytically active centers from each other (site isolation), thereby leading to high selectivity of the desired acrylonitrile product. A detailed reaction mechanism of propane ammoxidation to acrylonitrile is proposed. Combinatorial methodology identified the nominal composition Mo_0.6V_0.187Te_0.14Nb_0.085O _x for maximum acrylonitrile yield from propane, 61.8% (86% conversion, 72% selectivity at 420 °C). We propose that this system, composed of 60% Mo_7.5V_1.5NbTeO₂₉, 40% Mo₆Te₂VO₂₀, and trace TeMo₅O₁₆, functions with a combination of compositional pinning of the optimum orthorhombic Mo_7.5V_1.5±x Nb_1±y Te_1±z O_29± phase and symbiotic mop-up of olefin intermediates through phase cooperation. Under mild reaction conditions, a single optimum orthorhombic composition might suffice as the catalyst; under demanding conditions this symbiosis is additionally required. Improvements in catalyst performance could be attained by further optimization of the elemental distributions at the active catalytic center of Mo_7.5V_1.5NbTeO₂₉, by promoter/modifier substitutions, and incorporation of compatible cocatalytic phases (preferably epitaxially matched). High-throughput methods will greatly accelerate the rational catalyst design processes.     

Modeling of interdiffusion in poly(vinyl acetate)–poly(methyl methacrylate)–toluene multicomponent systems

Work on interdiffusion has been mainly carried out in binary systems in the past, and this work has focused on polymer–solvent (S) systems and polymer blends. To understand and predict the interdiffusion of two solids in the presence of one S, we present a new mathematical model based on the Onsager approach. Within our model, interdiffusion kinetics are described with a modification of the reptation model for long polymer chains, and the chemical potential gradient is used as the driving force behind mass transfer. The chemical potential is calculated with a Flory–Huggins approach. The model was validated with 29 Raman spectroscopy experiments in poly(vinyl acetate)–poly(methyl methacrylate)–toluene systems at 20 °C. Monomer mobilities (L _i,0s) were determined for both polymers to show the independence of L _i,0 from the chain length. The L _i,0s were found to be strongly dependent on the S content. With the knowledge of phase equilibria and L _i,0s, interdiffusion in the ternary polymer–polymer–S system could be predicted by the introduced model. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47092.     

立方ZrW_2O_8结构类型热收缩固溶体Zr_(1–x)M_xW_(2–y)M′_yO_(8–z/2)的研究进展(英文)

综合介绍了最近十多年,立方ZrW2O8结构类型固溶体Zr1-xMxW2-yM′yO8-z/2 (M:Hf4+,Ti4+,Sn4+,Al3+,In3+,Fe3+,Cr3+,Mn2+,RE3+;M′:Mo6+,V5+)的研究进展和主要研究成果。由生成等价和低价离子取代而制备的固溶体 Zr1-xMxW2-yM’yO8-z/2,可调整立方ZrW2O8结构类型热收缩材料的有序-无序相变温度、晶胞参数,提高离子电导率,热稳定性和机械强度,不失为一种改善热收缩材料性能的途径。此外,还列举了多种合成立方 ZrW2O8结构类型固溶体和制备陶瓷材料的方法。     

Ruthenium(II) acetylacetonato–sulfoxide complexes

The water-soluble Ru^II acetylacetonato–sulfoxide complexes, cis-Ru(acac)₂(DMSO)₂ (1) and Ru(acac)₂(meso-BESE) (2), were synthesized (BESE=1,2-bis(ethylsulfinyl)ethane=EtS(O)(CH₂)₂S(O)Et). Both complexes were characterized by ¹H and ¹³C{¹H} NMR, UV–Vis, and IR spectroscopies, as well as MS, elemental analysis, solution conductivity, and cyclic voltammetry, while the molecular structure of 2 was determined also by X-ray crystallography. All sulfoxide ligands are S-bonded. The complexes were tested against human breast cancer cells (MDA-MB-435S) using an in vitro MTT assay, a colorimetric determination of cell viability; IC₅₀ values of >2000 and 1500 ± 100 μM were determined for 1 and 2, respectively, while cisplatin exhibits an IC₅₀ value of 30 ± 5 μM.     

Electron microscopy of macroporous cellulose (acetate–co–butyrate)–polycarbonate semi–interpenetrating networks

Summary Summary Semi–interpenetrating polymer networks, s–IPNs, were prepared from cellulose acetate–co–butyrate (CAB), still containing 46% OH groups, and diethylene glycol bis allylcarbonate (CR39) which was crosslinked by free–radical polymerization initiated by benzoyl peroxide. Microstructure of s–IPNs (CAB/CR39) of relative weight proportions between 0.2/1 and 0.411 was examined by electron microscopy (TEM and SEM). Spheroidal compact objects of several µm diameter are randomly distributed within a microporous phase in which the pore connectivity was shown by density measurements. Such a microstructure is consistent with the formation of CAB polymer dispersed phase in a poly (CR39) network continuous phase.     

复合电解质BaCe_(0.8)Y_(0.2)O_(2.9)–Ce_(0.8)Gd_(0.2)O_(1.9)的化学稳定性

采用溶胶―凝胶燃烧法制备BaCe_(0.8)Y_(0.2)O_(2.9)(BCY)和Ce_(0.8)Gd_(0.2)O_(1.9)(GDC)粉末,并通过机械混合法制备不同摩尔比的BCY―GDC复合电解质粉末,在1 450℃烧结5 h获得BCY―GDC复合电解质。研究了复合电解质的化学稳定性及电化学性能稳定性。结果表明:BCY–GDC复合电解质在CO_2和沸水中的稳定性均高于单相BCY;当BCY―GDC复合电解质中的BCY摩尔分数小于70%时,试样在CO_2气氛和沸水中都具有良好的化学稳定性。基于BCY:GDC摩尔比为1:1的BCY―GDC复合电解质的单电池,在700℃工作20 h内的最大功率密度的稳定性高于基于BCY电解质的单电池。     

镍–磷–碳化硼化学复合镀层的研制(英文)

在由碳酸镍15g/L、次磷酸32mL/L、次磷酸钠15g/L、乳酸32mL/L、乙酸18g/L、丙酸3mL/L、二甲胺1.7g/L及碳化硼(即B4C)0～25g/L组成的稳定镀液中,采用化学镀的方法在低碳钢上制备了Ni–P–B4C复合镀层。其显微硬度采用韦氏硬度法测量,耐磨性用Taber磨耗试验机测量,微观形貌和组织采用扫描电镜和X射线衍射进行分析,耐蚀性以动电位极化及电化学阻抗谱测定。碳化硼的掺入提高了镍–磷合金基体的显微硬度、耐磨性和耐蚀性。Ni–P–B4C复合镀层颗粒粗大,具有爆米花式组织结构。     

碱–磷渣–粉煤灰混凝土力学性能和耐久性(英文)

研究了用碱激发磷渣_粉煤灰胶凝材料(atkali activated phosphor slag fly ash cement,AAPFC)制各的混凝土的力学性能和耐久性,并用扫描电子显微镜观察了形成的水泥石与骨料的界面结构.结果表明:相对于硅酸盐水泥混凝土,AAPFC混凝土具有强度高,弹性模量较低的特点;其抗冻性和抗氯离子渗透性显著优于硅酸盐水泥混凝土,但抗碳化性不及后者.硅酸盐水泥混凝土中水泥石与骨料界面上存在大量定向排列的Ca(OH)2,造成弱结合,而AAPFC混凝土中水泥石与骨料问结合紧密.     

3–(3,5–二叔丁基–4–羟基苯基)丙酸甲酯及新型抗氧剂的合成

简述了3–(3,5–二叔丁基–4–羟基苯基)丙酸甲酯的合成方法及以其为原料合成新型抗氧剂的方法,介绍了部分新型抗氧剂品种及性能。     

Characterization and adsorption behavior of newly synthesized sodium bis(2-ethylhexyl) sulfosuccinate–cerium (IV) phosphate (AOT–CeP) cation exchanger

A new cationic exchange material, sodium bis(2-ethylhexyl) sulfosuccinate (AOT) with cerium (IV) phosphate (AOT–CeP) has been synthesized. The characterization of the ion exchanger was performed by using infra red spectroscopy (IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermo gravimetric analysis/differential thermo gravimetric analysis (TGA/DTA/DTG) and elemental analysis. The ion exchange properties like ion exchange capacity, elution and concentration behavior of AOT–CeP were determined by taking the material into a column and elution of H⁺ was done by NaNO₃. The thermal stability of the ion exchanger was studied by determining ion exchange capacity after heating to different temperatures for one hour. The adsorption studies on AOT–CeP demonstrated that the material is selective for Cu²⁺, Pb²⁺, Cd²⁺, Zn²⁺ and Hg²⁺ ions. AOT–CeP was found to be effective for the separation of Cu²⁺, Pb²⁺, Cd²⁺, Zn²⁺ and Hg²⁺ ions in the presence of alkali metals/alkaline earth metals. This cationic exchanger was also effective for the removal of Cu²⁺, Pb²⁺, Cd²⁺, Zn²⁺ and Hg²⁺ ions in the presence of acid and other transition metal ions. Thus, AOT–CeP can be used for the removal of these ions from the waste water during its treatment.     

3–硝基–1,2,4–三唑–5–酮纳米多孔炸药及其制备方法(CN107512994A)

<正>将炸药进行微纳米化,能够大幅度提高能量释放速率,同时纳米特性将使炸药具有低的临界爆轰直径。中国工程物理研究院化工材料研究所于2017年开发了一种3–硝基–1,2,4–三唑–5–酮纳米多孔炸药的制备方法,它包括:将3–硝基–1,2,4–三唑–5–酮炸药溶于去离子水,在超